Just click the link, then click on the Microsoft Booth. It then shows the featured games, which are: Halo 3: ODST, Alan Wake, and Forza Motorsport 3.
Earlier IGN talked about 3 games from Microsoft at E3 that they were going to showcase. One was a game announced earlier (Halo 3: ODST) and the other 2 were unannounced. (Forza 3 and Alan Wake) Microsoft still considers Alan Wake to be unannounced. (Based on the latest 1up podcast)
So let the speculation begin!