Popfly Game Creator. The system is designed to be an easy way for pseudo-developers to pound out casual computer games, focusing on allowing projects to be started and finished without writing any code.
Ease of use aside, what they are actually pitching doesn't seem to be based in reality. It is the developers who know how to take ideas and put them into code properly that end up making good games, whether grandiose or browser flash games. While inevitably these types of developers get streamlined into ugly behemoths like EA, Microsoft's focus here seems to be a much younger, less skilled audience. They do make a good point, however, in that it might be a hook for younger people who are interested in future development careers.
Still, it seems like Microsoft is trying to craft the MySpace of simple parlor games. It will be interesting to see what this tool actually ends up being used for.