I'm not going to speculate on which games Microsoft will announce and showcase at E3 this year. But here are some general hopes for their conference.
First, Microsoft needs to make avatars worthwhile. They made avatars a big deal last year, but what can we do with them? They act as faces on a few arcade games. A single game, A Kingdom for Keflings, makes use of the full avatar. 1-vs-100 is a good idea, but that can't be it.
Second, this new motion-detecting camera should have some game applications that regular gamers can enjoy. The Xbox 360 will never have as strong appeal as the Wii to the same groups. The 360's marketing to regular gamers can't help but color its perception among casual gamers, and casual gamers aren't likely to care enough about games that they'll accept the hardware's notorious unreliability. Microsoft would have more success focusing on their present audience.
Third, I hope they discuss the issue of persistent online games on Xbox Live -- whether or not it's acceptable to charge players on top of the Xbox Live subscription; and, if so, how much. It's bad enough that we pay for multiplayer in games that don't have dedicated servers and are always disconnecting.
Fourth, for Pete's sake, have the courtesy to not announce things that won't be materializing this year or similarly set ridiculous expectations. The "New Game Experience" was a bad joke. I find it hard to get excited about Alan Wake since it was made a centerpoint at the 360's first conference years ago. Microsoft has a bad habit of greatly disappointing their players by setting up expectations they can't meet. It makes for an exciting press conference, but it undermines consumer trust in the long run.