Microsoft's conference is starting in a little less than an hour (1:30 EST). Some places you can watch it live:

GameTrailers: E3 2010 Coverage | GameTrailers.com
GameSpot: E3 2010 Latest Highlights at GameSpot
IGN: E3 2010 - Video Game Expo and Press Conferences - IGN
YouTube (IGN Partnership): YouTube - E3's Channel
1UP: E3 2010 Video Game News, Videos, and More
G4tv Online: E3 2010 Convention Headquarters On G4TV.com, E3 '10 Live On G4
Xbox (UK): Xbox.com | Welcome to E3