Back on topic now...
I remember saying over on Xboxhacker a while back about memory/cpu glitching... Only problem is the guy who found it (gligli) isn't 100% sure himself how it works, but the fact is it does. Something along the lines of reseting part of the CPU while keeping the rest active.
Pretty much, booting the CPU into a ready state, flushing (glitching) the CPU_RESET line resulting in unsigned code being executed (hash check comes back ok)
Clever stuff... I can see all the £££ signs floating round ppl's heads.