From Eurogamer: Unangst said Microsoft would "continue to invest" in Games for Windows, which apart from giving its games an Xbox Live-style service layer with friends lists, Achievements and the like, also insists that games be easy to install, support widescreen displays and include parental controls.
It all sounds promising. The one thing I was most impressed with on Xbox 360 is the whole integration and lack of configuration for games, if they can bring that to Windows Vista then a lot of people will be very happy.
Some ideas:
You can see how they could potentially take the experience index benchmarking framework and develop that into something that can adjust games visual quality, automatic updating and applying of patching without user intervention, matchmaking and the community features could all be very useful and add value to PC gaming. Even some sort of integrated anti piracy tool developed for Microsoft that doesn't rootkit your machine which would be less painful to consumers would also be an improvement over the current situation.