Press release posted on Black Industries page today announced the publication, at long last, of a Warhammer 40,000 RPG, titled Dark Heresy. There's been a lot of speculation on the forums that a 40k RPG was waiting in the wings; the mention of the 40k property in the early announcements from BI and Green Ronin made it sound like a likely outcome.
From the press release, it sounds like the RPG will probably be borrowing a bit from Games Workshop's Inquisitor skirmish game, which had a fair number of RPG elements to it when it came out. Future expansions- oddly described as "two further games"- will revisit the Rogue Traders of the early, early days of 40k, as well as one of the branches of the Space Marines (the elite Deathwatch marines).
Over the years there have been several unofficial attempts to create a 40k ruleset. Some have used the WFRP system (which will be the basis for the new BI game), and some have used homebrew systems, or other published rulesets (there's at least one d20 conversion floating out there on the net). One of the big issues that always comes up is scale. While certain games (Ars Magica, Buffy, and to a lesser degree WFRP) have dealt more or less successfully with having player characters of wildly differing power levels in the same game, 40k presents a more serious challenge. Players drawn in from the 40k tabletop game are going to want to play the types of critters that they've seen in their armies. But characters like Space Marines are a far cry more powerful than the sorts of characters to be depicted in the first version of the 40k RPG rules- members of an Inquisitor's warband. It will be interesting to see how BI handles the scaling issues- this may be why they're referring to the expansions for the 40k RPG as separate games.
An interesting development, though certainly not unexpected. I'm eager to see more details about what Dark Heresy is going to look and play like. Just as long as it doesn't push back the schedule for any WFRP products... ;)