The iPhone Dev-Team has finally released untethered jailbreak for iOS 4.3.1 via Redsn0w and PwnageTool. Except for the iPad 2, this new untethered jailbreak is compatible to work with all devices, including: iPhone 4, 3GS, iPad (1st-gen) and iPod touch 3G/4G on the newly released iOS 4.3.1 firmware.
This untethered jailbreak for iOS 4.3.1 is based on an exploit found by iPhone security expert and hacker Stefan Esser, who demoed it on his iPod touch last week before handing it over to the Dev-Team to do the rest.
iOS 4.3.1 was originally jailbroken last week using PwnageTool bundles (on Mac) and Sn0wbreeze (on Windows) but it was limited to tethered boot.
But now with this new version of Redsn0w and PwnageTool, you can jailbreak on the above mentioned devices, fully untethered on iOS 4.3.1.