There are very few games I would say I consciously wait for. I tend to make my decisions about games after they've been released, when I know I can walk down to the store and get it. The last time I think I really stressed about a release date was back when we used to scan .plan files of our favorite developers and designers.
Braid is a game I am waiting for. Jonathan Blow has been hinting on his weblog that the game is really close, but can't announce the release date due to some XBLA rule. He did mention, and so I will too, that this post on Joystiq gives some idea of the time frame. [psst, 4-6 weeks]
If you're like me and have very few games you get excited about these days, check out Braid.