Pwned

An Already Pwned device is a device which has already been flashed with a patched LLB and iBoot, and therefore doesn't signature check the code uploaded and can have custom firmwares restored from Recovery Mode. The exploits which can pwn devices are Pwnage and 0x24000 Segment Overflow.

Software Support
Some jailbreak software support a special jailbreak mode for Already Pwned Devices:
 * redsn0w (0.7-0.9.5)
 * PwnageTool
 * sn0wbreeze