It's been more than three years since X06, the last proper Xbox event that Microsoft have hosted, but now it would seem Microsoft are picking up the slack. They plan to host X10 in San Francisco on February 11. It would not seem to be a return to the two day mega event Microsoft previously held in Europe though as the event is only four hours long, and it may very well be reserved for North American media.
A number of big titles will be on display including Alan Wake, Crackdown 2, Fable III, Final Fantasy XIII, Halo: Reach, and Splinter Cell: Conviction. We assume Project Natal will also be given a lot of attention.