Oh dear god has this come back up again? There is a video floating around claiming to be evidence of 360 games running on 8. Whats been cut is mentioning its a showcase for a test system MS developed that allows you to run any program for which the translation routine exists. Theres other videos that go with it showing PS3 games and even OSX programs running using the same system

http://research.microsoft.com/en-us/projects/giano/