Some Apple devices are still downloading iOS 5.1, which was released yesterday, and the operating system has already been the subject of a jailbreak.
It has been reported that the iPhone Dev-Team have updated their Redsn0w jailbreak tool to allow users running iOS 5.1 to jailbreak their devices. The hack is slightly limited to products that use the A4 chip, meaning that the iPhone 4S and iPad 2 are not supported by the new workaround.
The jailbreak is still incomplete at the moment so prospective users will have to make do with a tethered jailbreak for now. The iOS 5.1 devices that are hacked with Redsn0w will have to be connected to a PC or a Mac in order to boot up. There is a semi-untethered boot method available but the device will only feature limited functionality until a tethered boot is done.
Source: Redmond Pie via Gizmodo