The day has finally come, comex has released Spirit, the first userland jailbreak since the 1.x era. It runs on the latest iPhone OS firmwares (3.1.2, 3.1.3 and 3.2). Spirit is an untethered jailbreak which comes as great news to many 3rd generation iPod Touch & iPhone 3GS users who have the MC models who were stuck with a tethered jailbreak for months.
It works on all the iDevices but on the iPad, all this is still sort of beta. Some packages in Cydia, not designed for iPad, might screw up your system and require you to restore.
You can download it from SpiritJB.com