Starting tomorrow you can pick up Moto GP at your local video game shop.
If you haven't gotten a chance to play the game, I highly recommend downloading the demo on the marketplace.
I thoroughly hate racing games (save burnout) but I found Moto GP to be pretty fun. Difficult, but fun nevertheless. You should have seen some of the spills I took.
It's the only 360 game coming out this week, it wins game of the week honors by default.