Well it's done renowned iPhone hacker takes the Ps3 a level higher by jailbreaking the system and allowing .pkg files to run on firmware 3.55 yes that's right homebrew on 3.55 is just around the corner. What Famous Geohot has done is that he has enabled the .pkg feature with a lv2diag.self after he has then signed the (NPRDM) self file and packaged it into a retail.pkg file without a signature. A file is then patched again on the flash so that it ignores the signature. What this does is that it allows homebrew to run from the XMB without the signature.
The video below demonstrates homebrew being ran on PS3 firmware 3.55:
YouTube - "Jailbroken" PS3 3.55 with Homebrew
GEOHOT WEBSITE: www.geohot.com