He managed to have read/write access to the entire system memory, and HV level access to the processor.

He states on his Blog:

"As far as the exploit goes, I'm not revealing it yet. The theory isn't really patchable, but they can make implementations much harder. Also, for obvious reasons I can't post dumps. I'm hoping to find the decryption keys and post them, but they may be embedded in hardware. Hopefully keys are setup like the iPhone's KBAG."

Maybe he has used the exploit which was used 2 years ago to get complete root access to the Playstation 3.

George Hotz says he has a lot of reversing ahead of him, as he now has dumps of the so-called LV0 and LV1. He has also dumped the NAND without removing it or a modchip.