Premier XNA Title
Vanguard: Saga of Heroes is a massively multiplayer RPG currently in development by Sigil Games Online, Inc. and funded and to be published by Microsoft Games Studios.
Sigil was founded by two major contributors to the EverQuest phenomenon. In addition to their credentials, they have announced that Vanguard will use the Unreal Game Engine and they will be using the Microsoft XNA platform for development.
Sounds like an awesome combination!