Pwnage tool is a mac-only jailbreaking tool developed by iPhone dev team. It is used to create custom firmware to prevent iPhone baseband updates. Pwnage tool is also used to change boot logos and add pre-installed packages to the IPSW you are creating.
PwnageTool also avoids any possible sync issues, but again it applies only to A4+earlier devices. If you unlock your iPhone with ultrasn0w or a commercial method, you must use PwnageTool to avoid updating your basebandotherwise you’ll lose the unlock. PwnageTool will also jailbreak+untether the AppleTV2,1 5.0_2B206f (unless you customize the IPSW further, you’ll have just basic SSH access to the device).
Pwnage Tool latest version: