You can jailbreak PS3 consoles with 3.55 Original Firmware (OFW) and below.
Consoles with OFW 3.56 and above might be downgradeable using a hardware flasher such as E3 or Progskeet.
You can check whether it is downgradeable by checking the SKU page on PS3DevWiki - link below.
Those currently using a (jailbroken) PS3 that has custom firmware (CFW), you can use PSN if you're using one of the latest 4.21/4.30/4.31 CFWs with Rebug's 4.40 Spoofer, however, the risk of getting banned is likely. Alternatively you may make use of XLINK KAI or XBSLINK to play with others, for more information, head over to the tutorials section.
PLEASE PLEASE PLEASE stop asking and creating new threads about these subjects. Everyday we have members asking the same thing. Do you want to help us stop this? If ANYONE creates a thread asking about jailbreaking or playing online with those firmwares please direct them to this thread .
Last edited by GSTAR01; 23rd March 2013 at 08:00 PM. Reason: Updated info
This needs to be updated/removed. It's out-of-date!