Control your games with your Android phone.
Microsoft's "Smart Glass" technology will link all of your smart devices together - whether you have a Windows PC, an Android phone, or an iPad. If you find yourself watching a movie on a tablet during a vacation and come home, a simple button press will transfer the movie to your Xbox to watch it on your widescreen TV. Your tablet, then, becomes a secondary source of information about the movie and cast.
With games, we saw that the player could use the tablet to redraw a Madden NFL play on the fly with his iPad, and control the passes and action accordingly. Exploring a particular place in Halo 4 would unlock a Waypoint that might show you some new Halo lore. While you were exploring that on your tablet, you might get a notification for multiplayer, which you could accept (on your tablet) to join (on your console).
You will be able to use your tablets and smartphones to browse the internet via your Xbox 360, with built-in Internet Explorer functionality that will be coming soon.
Essentially, this is Microsoft getting the jump on the Wii U by adding that sort of cross-device functionality with hardware that many gamers and tech-heads actually already have.