Here are few more facts about Userland Jailbreak Spirit as posted by iPhone Dev Team :
Other things about Spirit that are useful to know:
* Spirit is an untethered jailbreak.
* Spirit works on all devices. (However, the redsn0w and PwnageTool flows will continue to work on those devices they’ve always worked on)
* Spirit does not include a carrier unlock. (Please don’t bug @comex about that)
* Spirit requires your device to be activated or hacktivated