Check out this video of plain vanilla OS X running on the AppleTV.
semthex from Hackint0sh.org, in collaboration with AppleTVHacks.net has done it again! A complete replacement to the Mac OS X kernel has been built which allows the full version of Mac OS X to be run on an Apple TV.
Semthex wrote a processor emulation for the kernel, to sidestep the hardware restrictions that previously disallowed Mac OS X from running on the Apple TV.
This is now a $300 micro-mini, and an obvious opportunity for a more customizable media center.