A long time ago, a hack was found so you can play copied games and backups on a Xbox 360. So the hacking went dead except for a little blip here and there. Well now it turns out that people have already got Linux on it and have been working on running unsigned code on it. Maybe I wrote the platform off too soon?
From Xbox-scene.com,
Since we have an exploit in the hypervisor (kernel 4532 and 4548) and recently found a way to downgrade to these kernels, some hackers over at the XBH forums are working on a way to boot homebrew code on the Xbox360. Linux was already done via the linux bootloader, but for homebrew we'll need another bootloader obviously that will allow to boot 'unsigned' xbox 360 code.
If this works, then I wonder if someone will convert xbox media centre over to that platform too? Imagine Linux, PC, Xbox, Xbox 360 and PS3 all being choices for XBMC.