A pair of hackers have discovered a method of bringing iOS apps to HDTVs via a jailbroken Apple TV.
Developers Steve Troughton-Smith and Nick "TheMudkip" built the bridge using an alternative to Apple's built-in SpringBoard (the home screen) called MobileX. The demo Apple TV was jailbroken using the latest untethered version of Seas0nPass and runs webpages and apps like Maps, YouTube, Facebook and Cydia through SSH and VNC connections.
As you can see from the video, MobileX struggled a bit with lag and crashes, so it isn't quite ready for public consumption. But eager developers can download the necessary code to allow the Apple TV remote to control apps when MobileX finally makes its debut.
Apple TV offers some support for MobileX features through AirPlay Mirroring, but it's limited to the iPad 2 and the iPhone 4S -- with the possibility of Mirroring with OS X Lion coming soon -- and only certain apps are compatible.
The problem with this hack is that iOS apps are controlled by touch, and without the clever use (and additional cost) of Apple's Magic Trackpad or a second iOS device, navigating iOS apps on an Apple TV would be awkward at best and nonfunctional at worst.