Read more about it here!
The reason I am surprised is that the timing seems odd. I was expecting it a bit later, after Rogue Trade picked up steam and got a few more supplements added to the lineup. But maybe this was needed after those pictures from GW revealed a bit more than they should last week.
Still, I think it is tremendously exciting, and I'm hoping that I can find some energy to run a Dark Heresy/Rogue Trader/Deathwatch crossover some time next summer. Given I get some interest from my players for such a setup of course.