Other than the WinMCE output display trick, which isn't what you're asking, see the following:
http://www.xbox-scene.com/software-xbox360.phpNext time, please check a bit before asking if this and/or XBMC (and or any homebrew) is running on the 360.
Hello world and some linux, which shows promise, is about what's there *for the moment*. Check the news page for more info and links.