>> crippled Sony hyper-visor layer
I think bypassing the hypervisor is only way this box would ever be interesting for alternate OS hacking. Sony is using the hypervisor as a 'HAL' so that they can modify the hardware builds in the future and older games will still run.
If OS4/AROS/etc. could run on the metal, they would scream, and the co-processors would be a blast to play with for audio/video/image processing, and 256 or 512 Mb RAM would be plenty!
If the *visor could be disabled by hardware modification, the PS3 wouldn't play games anymore, but I for one wouldn't care - I would live to have a $600 3.2GHz Amiga! Hey, I still have the receipt for my $1000 '040 Warp Engine, and it was just an accelerator.