I just read an article which said that, if you looked through the ventilation grates on the Xbox360 demo kiosks, what you saw actually running the demos were Macintosh G5s.

I found that so very very amusing.

It actually makes sense when you think about it, since the 360 is going to run a PowerPC processor and an ATI graphics chipset. Still. The idea of Microsoft's game console being based on a Macintosh architecture is just wonderfully ironic.