updated 10:35 am EDT, Wed October 13, 2010
Original exploit kept as reserve weapon
Following swiftly after the launch of Limera1n, a second iOS 4.1-compatible jailbreak has been released, greenpois0n. Users can open up the iPad, iPhone 4, iPhone 3GS and third- or fourth-generation iPod touch to unofficial apps and customization. An RC2 version of the hack was initially posted before being pulled and replaced with RC3.
Promised in a future update is support for the Apple TV, as well as the second-generation Touch. The release is officially Windows-only at present, though a Mac version is planned, and a Linux download link is already live. iPhone 4 owners are cautioned to use TinyUmbrella to preserve baseband if coming from pre-4.1 firmware.
greenpois0n was originally slated to launch two days ago using another exploit, SHAtter. The code was then switched to the bootrom USB exploit developed by geohot, however, with the idea of keeping SHAtter in reserve in case Apple closes the current hole. Apple regularly works to sabotage jailbreaking techniques.