Here's the official announcement, which was entitled "Dawn of War II: Retribution on Steamworks":
The official announcement. That's right, no Games For Windows Live for Retribution:
We are excited to announce that Warhammer® 40,000®: Dawn of War II ® - Retribution™ will use Valve’s Steamworks networking and matchmaking to provide co-operative and competitive online play. This new back end will allow players to invite friends into matches from their Steam friends lists, and take advantage of the full set of Steam community features including groups, achievements, and Steam overlay chat channels. We are also going to include an all new matchmaking and ranking set up, built specifically for Dawn of War II – Retribution.
The move to Steamworks will also allow us to provide features like guest passes, free multiplayer weekends, pre-loading and the ability to provide fast turn-around on future patches and updates.
To accomplish this transition, Dawn of War II - Retribution will be a completely stand alone title in the series and will provide multiple campaigns to play, as well as all six multiplayer races, with new units for each of the existing five races and one new unannounced one. In a change from our previous strategies with expansion packs, we will not be patching this content back into Dawn of War II and Chaos Rising.
Owners of Dawn of War II and Chaos Rising will get the chance to try out the full set of Retribution’s Steam features in a multiplayer beta that will take place in the new year. More details on the beta will be announced at a later date.
Dawn of War II and Chaos Rising will continue to operate on Games for Windows LIVE, in order to preserve the owners of those titles ability to earn LIVE achievements as well as their established friends lists.
We are going to have more exciting announcements in the coming weeks, so stay tuned.
Thanks for playing!
In an interview with PC Gamer, Jeff Lydell, Retribution’s producer, had this to say when asked why they made the move to go with Steam: "Mostly it was related to the end-user experience. Dawn of War II and Chaos Rising are hybrids of Steamworks and Games for Windows LIVE, and require the owners of those games to log in to both to play. We’ve always thought this was cumbersome, and only implemented it because back in Dawn of War II’s development, we needed digital distribution and matchmaking features from both platforms."
Since then both Microsoft and Valve have worked to catch up with each other, and on Dawn of War II – Retribution, we’ve decided to utilize the Steamworks SDK for networking and matchmaking."
The folks over at Relic and THQ have also released a video highlighting the Eldar. We've included it below for those that haven't seen it yet.
Dawn of War II: Retribution is due to hit March 2011.