Sn0wbreeze also know as PwnageTool for Windows, this tool will untethered jailbreak iOS on iPhone 4G, iPhone 3GS / 3G, iPod touch 4G / 3G and iPad without basebande update , setup custom boot logos, activate your iPhone, set a root partition size, build custom firmware, install SSH, and more.
[Updated for iOS 6.0.1 - 6 - 5.1.1 ]
Sn0wbreeze 2.6 ( iOS 4.3.2 jailbreak for iPhone, iPad, iPod touch) has just been released. This version support Ultrasn0w as well ! so you can unlock your iPhone on iOS 4.3.2 if you have a unlockable baseband.