Well, I want to reinforce what NDT said, specifically this will not really help too many people (which is why it should NOT have been public) as you can not stick the drive in your PC and decrypt it. We believe it uses some form of AES to encrypt the data (just like the flash filesystem).
Although certain chunks of data can be decrypted with this method, its mostly the luck of the draw. Random encrypted data is being swapped around, with no table, no filesystem, basically shooting in the dark, which makes it nearly impossible to know what files you have, where they belong, or even their file names!
Now, assuming someone spent the time to decrypt the entire drive, find a filesystem, map it all out, it would be a step in the right direction, but that could take forever to accomplish.
However, with the exception of some assets, such as pictures and videos in certain areas (ie, photo/video, and some game data), everything on the hard disk drive (and the flash, too) is encrypted with yet another layer of encryption (namely, the SELF encryption). For example, take a game that was bought and installed via PSN. With the exception of the SFO, and PNG's, the SELF, and many packaged assets are all still encrypted!
Finally, any flash data stored on the HDD, is yet again, encrypted, so alas, no help there!