I think this is an excellent idea. I remember reading one of the recent Peter Molyneux interviews on Gamespot, where he talked about how the Internet allowed the companies to reach out directly to their consumers in a manner never possible before. The ease of taking feedback and suggestions and all that, and the way I see it, this move by Steam is a perfect example.
IMO the idea is so good, I'm surprised no one else ever thought of it before. Certainly going to be a good way to launch indie games.