Update (01/25/2010): DBM 4.40 comes with a new and improved range check frame and support for the new bosses.
Changelog:

DBM 4.32 is now available for download. It supports World of Warcraft 3.3.x and comes with boss mods for Icecrown Citadel.
Most of the timers and warnings in the new boss mods are based on PTR information and might be inaccurate. We will release a new version of DBM with updated boss mods in few days and another new version next week (if necessary).
You can help us by providing information like combat logs, chat logs, or spell timers. Please refer to this thread on the forums for details on this.

Update (10/31/09): DBM 4.29 had a bug which broke a lot of warnings in the party module, all warnings that announced targets of spells were affected. DBM 4.29b-r2049 fixes this bug.

Deadly Boss Mods 4.29 is now available for download, it adds a lot of new options. For example, you can now change the font, color, and position of the special warning (the huge blue text in the middle of the screen).

Changes

WoW is an awesome game, but sometimes we need to take a break - give our minds a chance to process, our fingers time to rest, and slots online are excellent ways to do this. There are definitely other ways to take a break, and you are recommended to take time away from your computer from time to time to reduce eye strain. Then you can get back to WoW and enjoy!

The latest version of DBM (4.28-r1673) has been downloaded 1,022,656 times in the past three weeks! This is the first version with more than one million downloads, the old record was held by Version 4.23-r1351 with ~900k downloads.

Detailed download statistics:

Thank you all for making DBM such a success :)

Creating powerful World of Warcraft addons like Deadly Boss Mods is easier than you probably think. You can start developing your very own AddOn right now with my book Beginning Lua with World of Warcraft AddOns

There are no prerequistes (except for a copy of the game), so everyone can be a World of Warcraft addon developer. The book is full of powerful (but yet simple and easy to understand) examples. It will teach you everything you need to develop amazing addons just like Deadly Boss Mods!

You can buy Beginning Lua with World of Warcraft Add-ons on Amazon.com or get more information about the book on this page.

Deadly Boss Mods 4.28 comes with a lot of updates for the Trial of the Crusader boss mods.
All changes:

Deadly Boss Mods 4.27 adds support for Onyxia and fixes a few bugs.

All changes:

While the options for addons are endless, really good ones are hard to come by. We hope that this site gives you a feel for what can be acheived with an addon when the right amount of time and effort is put in. Perhaps you could create your own add on (some information can be found on this page) and let us know about it. Perhaps you could even create an addon which allows your character to become an expert in bingo sites, or other games of chance while you are in the virtual world. Thankfully, when it comes to your imagination, the world is your oyster!

Deadly Boss Mods 4.26 contains timer updates for the Crusader's Coliseum, especially for the heroic version of the bosses.

All changes:

More news: DBM is moving to a newer, better, and faster server! This should prevent downtimes on patch days. The transition should be smooth, there shouldn't be any downtime or whatsoever.
Update: Transition complete, this is the new server :)

Update #3 (09/02/09): Version 4.25 contains a lot of updates and bug fixes for Crusader's Coliseum. The new pvp boss Koralon is now also supported.
Update #2 (08/12/09): Version 4.23 contains updates for the second boss in Crusader's Coliseum and a few bug fixes.
Update #1 (08/09/09): Deadly Boss Mods 4.22 fixes all issues related to dungeon difficulty. It also contains updated boss mods for Crusader's Coliseum and a brand new battleground mod for Isle of Conquest.

Deadly Boss Mods 4.20 is available now. It has basic support for Crusader's Coliseum and contains a few other fixes that were reported over the past weeks.
The alpha version will be updated every few hours as we do these encounters on the live servers.
This version also contains a few performance tweaks that should improve overall performance.

Deadly Boss Mods 4.16-r1202 is now available for download, the most important change in this version is that we fixed the Emalon boss mod which was broken since 4.15-r1143. Another important new feature (which already exists since 4.15 but it wasn't mentioned here yet) is that there is a new option in the spam filter tab that disables the "new version of DBM is available" notification.

We have been constantly developing the Ulduar boss mods since the release of World of Warcraft 3.1. The alpha download package on this site was updated multiple times per day but there was no good way to inform you about the changes. Updating the previous newspost every time we made a change was obviously not the best solution as the post grew too big and became unclear.
I have just set up an RSS feed containing the latest changes in the downloadable alpha-version. The URL is http://www.deadlybossmods.com/rss/DBM_Alpha_Changes.xml. This feed is automatically generated from the subversion logs meaning it lists every single change. I will still update this site every time there is a new version or a major change so you don't need to use the RSS feed if you don't care about the alpha version.

You can also follow me on Twitter if you have a Twitter account. I will post updates and other stuff there if a few of you actually have a Twitter account and follow me.

Update #23: DBM 4.14-r1057 fixes a lot of minor bugs in the Ulduar boss mods and adjusts timers.
Update #22: I'm currently looking for a new way of publishing the latest changes to the alpha versions as these updates in this news post are somewhat unclear. I'm considering to use Twitter to keep you guys up2date...but is anyone here actually using Twitter and willing to follow me?
Update #21: DBM 4.13-r1021 fixes a bug in the russian Naxxramas localization that lead to an error message. The error only affects russian clients, you don't have to update if you don't mind the error message.
Update #20: DBM 4.13-r1019 is now available for download. It contains all changes mentioned below. We have received a few reports that DBM caused a #132 critical error (which, in theory, cannot be caused by a mod, but well yeah...theory). This should not longer happen with DBM 4.13. However, we didn't manage to reproduce this bug, so I can't guarantee you that it is fixed. Please let us know if experience crashes related to DBM.
Update #19: There were a lot of changes in the alpha version over the past few days. A lot of Ulduar-10 spell IDs have been added and many Ulduar boss mods had their timers adjusted (and we've added a few new timers). Especially the Yogg-Saron mod received a major update :)
Update #18: Our separate addons "Spell Timers" and "Raid Lead Tools" just received another update for Ulduar. You can find these addons on the downloads page.
Update #17: We improved a lot of boss mods by fixing minor bugs and adding/fine-tuning timers.
Update #16: DBM 4.12-r940 is now available for download, it contains all changes mentioned below.
Update #15: The Yogg-Saron mod received a major update and we added more Ulduar-10 support.
Update #14: Added basic support for Yogg-Saron!
Update #13: The boss health frame can now display vehicles, this means it now works properly at Mimiron.
Update #12: DBM 4.11-r905 is now available, it contains all changes mentioned below.
Update #11: Fixed some a lot of Ulduar 10 spell ids.
Update #10: Updated the Emalon mod, it now shows a timer for overcharge.
Update #9: The Mimiron mod received a few updates: the health frame now works properly and the phase detection works better. It now also detects if "Dark Glare" is interrupted because the target dies while spinning up. This detection requires multiple players in your raid to have the latest version of DBM installed.
Update #8: Deadly Boss Mods 4.11-r869 contains all the changes mentioned below, the Ulduar support is now pretty good :)
Update #7: Updated the Kologarn, Auriaya, Freya and Hodir boss mods. We also added a boss mod for the new Wintergrasp boss :)
Update #6: Update your chat mods (especially ChatMOD is known to cause problems and there is no new version --> disable it) if you still have problems with getting whispers displayed. This is not a bug of DBM and we therefore cannot fix it.
Update #5: I just updated the stable release from 4.10-r812 to 4.10-r840, this updated download package contains all changes mentioned below.
Update #4: The configuration menu of boss mods just received a small update, they can now shows tooltips for spells. The only mod that currently supports this is the XT-002 boss mod but we will update the other mods as well.
Update #3: The XT-002 mod just received a major update and should be fully functional in the latest alpha package!
Update #2: We just updated the Razorscale (turrets) and Ignis (flame jets, scorch) mods with new timers and warnings. This change is available in the 4.11 alpha package.
Update #1: Update DBM and your chat mods (Prat, WIM, etc) if you are experiencing issues with whisper messages.

Deadly Boss Mods 4.10 comes with basic support for Ulduar, but most boss mods still need a lot of fine-tuning and a lot of timers are still inaccurate and some are even missing as they are based on PTR data. We will work hard during the next days and weeks to update all the Ulduar mods!

The latest Ulduar updates are always available in the svn build of DBM and we will also push updates on sites like Curse.com and WoWInterface periodically. However, we expect these sites to be quite slow over the next few days so the best way for you to get the latest Ulduar boss mods is downloading them here.

This news will be updated every time we update or fix a boss mod for Ulduar.

Blizzard put a UI Add-On Development Policy on their web page a few days ago. It basically says that addons must be free of charge, the source code needs to be a "freely accessible" and addons must not include ads or solicit donations. The main "target" of this policy is obviously Carbonite as there is a pay-to-use version and they planned to distribute a free version as adware.
The official UI & Macros forum is full of threads discussing this new policy. A lot of people are upset about this new policy, one thread even suggests that addon authors should "pull down their addons". A few authors even did discontinue the development of their addons.

But what is everyone upset about? Seriously, did anyone really expect that Blizzard would allow an addon to show advertisements in World of Warcraft? Did anyone really think that Blizzard allows addons to be sold?
But there is this one point in this new policy that is worth a discussion:

So the real question is: why do all the addon authors out there write World of Warcraft addons?
The team behind DBM does it for fun as a hobby and certainly not for money and I assume that 99.9% of all addon authors code for fun. The only commercial addon is (or: was) Carbonite. The whole new policy only affects Carbonite and in-game donation buttons. If you had a request for donation in your addon: replace it with a link to your web site. This is not prohibited and having donation buttons or ads on your page is also allowed.
Discontinuing addons due to this new policy leads nowhere. You should write the addons because it's fun for you. If it's not fun anymore, stop doing it.

In total, we don't see any reasons to protest against this new policy and we will thus continue working on DBM. There are lot of awesome new features and boss mods planned for the upcoming releases.

P.S.: @Blizzard: Is it really necessary to ban donation requests from addons completely? The only thing you got from this point in the policy was a forum riot. I think unobtrusive paypal links should be allowed if an addon author really thinks it is necessary.

[19/3/09] Update #3: The latest alpha-version has an updated version of the Freya mod for EU-PTR testing tonight! Feedback thread

[18/3/09] Update #2: The latest alpha-version of DBM 4.10 (download) now uses more robust chat filters that also support the old chat filter API. This means that the alpha now works on the live realm and problems with old chat mods on the PTR are now less likely.

[18/3/09] Update #1: A lot of people are currently reporting that DBM breaks their chat on the PTR when using a chat mod like Prat. This is not a bug of DBM. The reason for this problem is that Blizzard updated their chat filter API and the latest alpha version of DBM already makes use of this updated API. But many chat mods still use the old chat filter API, making them incompatible with every mod that uses the new one.
Having this problem on the live realm means that you installed the alpha of DBM 4.10 there. Please use DBM 4.0.x on the live realm!

We are currently working on Deadly Boss Mods 4.10 which will support World of Warcraft 3.1.0 and Ulduar.
DBM 4.0.x does not work in the PTR, please use the current alpha build of DBM if you want to play on the PTR. That alpha build does not work on the live realm, so don't use it there!

Update #5: Version 4.05-r638 is now available. This update fixes a few bugs that occurred in 4.04. A detailed change log and a list of known issues can be found in this thread.

Update #4: Version 4.04-r623 is now available. It brings major updates for all party mods and a completely new Sartharion mod. Some Naxxramas boss mods were also fixed & updated. All localizations also received major updates. A detailed change log and a list of known issues can be found in this thread.

Update #3: Version 4.03-r535 is now available. It updates nearly all boss mods by adjusting timers and adding new warnings. You can find a detailed change log in this thread.

Update #2: Version 4.02-r464 is now available. It updates nearly all boss mods (adjusted timers, new warnings etc.)

Update #1: Version 4.01-r441 is now available. It fixes some party-mod related error messages.

Deadly Boss Mods 4.00 is now available for download! It already supports Naxxramas, Chamber of the Aspects and Eye of Eternity. But these boss mods are based on the beta version of WotLK, we will do Naxxramas as soon as possible to update them if the bosses changed since the last beta build.

If you want to see DBMv4 in action: have a look at our updated features and screenshots pages with new DBMv4 screens.

DBM 4.00 uses a new folder structure. Please delete all old DBM_* folders before installing DBM 4.00! Updater-fail: You also have to delete them manually if you are using the Curse updater!

P.S.: We are still looking for people who are willing to help us translating DBMv4 into the following languages: koKR, esES and esMX. Contact me at tanadu@gmail.com if you want to help!

Update #2: 4.00 r401 has new and improved pvp mods! This version also fixes a lot of bugs. The final version of 4.00 will be released one day before the start of WotLK.
Update #1: 4.00 r304 fixes a major bug, please update if you are using r303 or older! (see forums for details...)

Deadly Boss Mods 3.30 supports World of Warcraft 3.0.2 and is available for download now!

Changes:

P. S.: We will continue to develop DBM in WotLK. If you didn't pre-order Wrath of the Lich King yet: you can do it here on Amazon.com (free shipping to U.S. addresses)!

Deadly Boss Mods 3.22 is now available for download!
Changes:

Arcane Orb now shows up in the combat log! But DBM 3.20 was looking for the wrong spell id as I just took the spell id that was used for Arcane Orb damage messages.
This is fixed in DBM 3.21 (available for download NOW!) - and it's the only change in 3.21 ;)

P.S.: DBM 4 will be released with Wrath of the Lich King and will have some awesome new features!