* Runs any of the 500,000 apps in the App Store w/ iPhone/iPod/iPad as controller.
* AirPlay becomes more fluid, maybe uses new Bluetooth chips in the 4S (currently uses wifi and can be extremely laggy depending on your home wifi setup).
* Opens up new API that allows apps to overlay menu/images over TV signal (Don't like ESPN's stats on the game? Download XYZ app w/ real time stats + chat.)
* Allows Siri on iPhone 4S to control the TV, setup DVR times, search through recordings, etc.
* Announces a deal w/ TWC/Comcast/Verizon/etc to replace their cable boxes reducing my number of remotes from 3 to 1 (or 0 if I can use my iPhone).