There hasn't been an event by Microsoft like this in a few years but
X10 will be taking place this year. The four hour event will showcase some of the upcoming Xbox 360 games and technologies. The date of the event is February 11th at the Terra event center in San Francisco.
Besides the requisite upcoming games being shown such as
Alan Wake and
Crackdown 2, you can expect
Project Natal will be there as well. I'm anxious to see how well the implementation is now and I'm betting we'll be hearing a lot coming out of X10 on this. Too bad it's only a short four event but it will be a nice little tease before E3.