I cannot keep these Warhammer 40,000 games straight, and I say that as a fan of the property. There's an MMO in the works called Eternal Crusade which looks halfway decent, as evidenced by the snippet of early gameplay footage found in this developer diary.
Let's be frank -- it looks like Space Marine. I am okay with this. More than okay, actually, since we never did get a sequel to that game and its mechanics deserved one.
The fact that Behaviour Interactive is handling development has me cautious given the studio's prior work, but what's shown here has convinced me to at least keep an eye on Eternal Crusade.