If this doesn't rock your world, then you must already be dead:
You can see a high-res version here. Over at Bell of Lost Souls, the speculation is that the final line of the trailer indicates that the Tyranids will be introduced in DoW 2: I think that sounds very likely. They're the only missing race in the game, so if only for the sake of completeness, I'm sure they'll be introduced sooner rather than later.
One comment on BoLS is salient:
I would gladly fork over reasonable sums of cash for a feature length 40k film of that quality. Doesn't have to be in theaters (though that would be awesomely insane on IMAX), direct to DVD is fine. A series available on DVD would be spectacular as well.
Here's hoping. GW has explored almost every other medium for their product (let's count them: music, novels, audio books, comic books, video games, artwork, even clothing), but there's never been a proper movie or TV series (apart from the never-to-be-seen Damnatus). Now that the technology is here that would do justice to 40k, it's time GW pulled their finger out!