Some useful facts to know are:
- Spirit requires your device to be activated or hacktivated
- 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.
The Spirit jailbreak will be best for newer devices such as iPhone 3GS, iPod Touch 3G, and iPad.
To read the complete article, click here.
Source: iPhone Dev-Team Blog