The Dev Team states :.
The 4.3.1 untether exploit comes up thanks to Stefan Esser (@ i0n1c on twitter), a security research worker based in Germany. Stefan has a long history of vulnerability research, and ironically his first contribution to the iPhone jailbreak community was improved protection last year he beat Apple to the poke and implemented ASLR for jailbroken iPhones with his antid0te framework. Were happy to see that Stefan then turned his iPhone attention over to an untethered jailbreak exploit! .
The jailbreak currently supports the following devices :.
iPhone 4 (GSM).
iPod Touch 3G and 4G.
iPad 1 .
Apple TV 2G (PwntageTool only).
The clearly seen hardware missing is the iPad 2 but the Team explains that the untether bootrom exploits used in the past do.