Minor correction. At 27c3's "Console Hacking 2010" talk. Geohot's Hypervisor work is mentioned at 4:25 or so. Described as "really unreliable" and "eh whatever" due to requiring hardware modification and only granting rudimentary hypervisor access.

These were the same people that then went on to explain how they reverse-engineered the encryption keys of the PS3 to enable "fakesigned" code to be installed