Earth? Let's hope that is just one small part of the game or where the big end, face off will be. I can't imagine the reapers just pawning one planet at the time. But, hell, the trailer looked great. The ToR trailers where sweat; but this one takes it a step further.
Anyway, I can see that ME3 will be about massing up your epic army, depending on what you did in the previous games, you get the whole galaxy or just a few select races who Shepard spared x-D
Oh, well, awaiting further news.