PS3 hacker claims custom firmware revives 'Other OS' in 3.21

As the latest system update for the Ps3 (3.21) axed the ability to install another operating system on it.  The person who in January claimed to have “hacked the PS3.”  Now claims to have created a custom firmware update that  reintroduces the Other OS feature to original PS3 units and potentially enables the feature on the Slim systems as well.

Geohot writes on his blog that this can be installed  just by restoring a PUP file, but only from 3.15 or previous.