Microsoft also announced an XNA Creator section of the Marketplace, where the users will be able to try out upcoming XNA created games - for free! First out here is a video of the USA-created JellyCar.
Update: Added some gameplay for the very funny Little Gamers.
Update 2: Next up is the Dodgeball game; Rocketball.
Update 3: And here is the garden simulator rising, Culture.
Update 4: The Dishwasher: Dead Samurai gets its own video. What an awesome game!