I think it's an interesting idea, and a smart move on Microsoft's part, but I think AndyFromMonday's got it right. The Kinect seems capable of amazing things (such as 3D image mapping [http://www.youtube.com/watch?v=XRvzap3wUvU], incredibly accurate tracking [http://www.youtube.com/watch?v=8vcacRA7O5g], etc. [http://www.youtube.com/watch?v=4V11V9Peqpc&feature=fvwrel]) but it seems nobody's really figured out the proper format for a game on it. This was sort of the EyeToy's problem (though granted the Eyetoy didn't work nearly as well, mechanically speaking). Lots of gimmicky games based strictly on the movement aspect came out, but nobody ever figured out how to get a big title or a long-term game to work smoothly. Maybe by putting it on Windows and making it even more accessible to modding and developing things for, somebody will get it figured out.
And even if no game-related discoveries are made, it does open a countless number of doors for computer functionality. Imagine running programs with the kinect, or interactive power-points, or interactive iTunes visualizations, or running Audiosurf with Kinect.