Microsoft have just released the XNA Game Studio 2.0. Which is supposedly a big improvement on the previous version, which for all its good intentions hasn't really set the user-generated content scene alight like MS were probably hoping it would. The newer, bigger, meaner XNA adds a bunch of new features to the service, chief amongst them the ability to craft cross-platform (ie 360-PC) multiplayer games. It'll also allow developers to code matchmaking into their multiplayer titles. Those with piqued interests, more info can be found below.