Translated with DemonHades:Today, numerous official debug firmwares have surfaced for developers to take a peak at. Versions 3.50, 3.55, 3.56, and 3.60 were leaked by a developer who goes by the name of ConsoleDev. These firmwares are originally designed to run on official development hardware known as PS3 Test (Debugging) Units. The units are only given out to official Sony developers, but some of these consoles have found their way into hackers' hands over the past few years.
In addition to these firmwares being useful to owners of debugging consoles, they are also used in the development of Rebug custom firmware. The official debug firmwares are generally not useful to the average user. However, they are available for download below for anyone that wants to take a look at them.
3.60 – Download – D9D16378DD66AACCA6EF0FC8604F9F67
3.56 – Download – A42F46B276DAC43851250526A8A8CB7A
3.55 – Download – 3B6EBC594DE5586B5E289225F6D3164A
3.50 – Download – 0E4D8BDBBA47382C2BE4242F3327E1A1
From web chat:Our friend and fellow ConsoleDev leaves us in the web chat several FW Debug from version 3.50 to 3.60 , so can investigate further and find a possible solution to exchange keys
Downloads:Originally Posted by ConsoleDev
>>Removed due to contested legality<<
News Source: PSGroove.com - 3.50, 3.55, 3.56, and 3.60 Official Debug Firmwares Leaked
Thanks to PSX-SCENE memmber NuclearAqua for the news!