An anonymous person at the German 23C3 Hacker Congress showed what could be an Xbox360 hack/exploit during one of the 'Lightning Talks'. Lightning Talks is a daily event at Chaos Communication Congress (C3/CCC). It consists in one hour of several short (limited to 5mins) talks.
In a very short presentation a masked 'hacker' showed an Xbox 360 booting up King Kong (the game, by ubisoft). After loading the game a screen pops up showing an Xbox 360 logo, a Mac logo and Tux (the Linux Penguin) and the words "coming soon...". I also noticed a small PCB is hanging out of his Xbox360 and he's using a laptop (Apple Macbook pro?), but it's not really clear what he's doing with it.