XBMC Media Center has released a version of their software that will run on the iPad, iPhone 4 and new Apple TV. XMBC is a free media player that began life on the Xbox but has since grown to be a multi-platform solution.
XBMC Media Center (formerly Xbox Media Center) is a free and open source cross-platform media player and home entertainment system software with a 10-foot user interface designed for the living-room TV. Its graphical user interface allows the user to easily manage video, photos, podcasts, and music from a computer, optical disc, local network, and the internet using a remote control.
The software is not available through the App Store, and requires a Jailbroken Apple TV or iOS device. You can follow our complete guide on How to jailbreak your Apple TV.