updated 07:35 am EST, Thu March 8, 2012
iOS 5.1 jailbroken in limited form
The iPhone Dev Team has detailed a very early jailbreak method for the now official iOS 5.1 update. Beta 6 of redsn0w 0.9.10 will crack all devices based on the A4 and earlier. With the exception of iPhone 3GS units with older firmware, however, the jailbreak is tethered and will need to be reused every time the device is given a hard reboot.
Carrier unlocks using ultrasn0w should work, but only for pre-5.1 basebands and only after loading custom firmware that uses the earlier cellular code. iBooks also won't work until a future update. Second-generation iPod touch owners do get wider jailbreak support.
The tool is available for both Mac and Windows users. Dev Team members haven't said how soon those with A5-based devices could get the option, nor whether they would have an iOS 5.1 baseband or untethered jailbreak. Any hacks for the 2012 iPad are likely distant even after the tablet arrives, as it's using both a new processor and a completely new cellular chipset on 4G versions.
As with any jailbreak, Apple doesn't provide help for modified firmware. [via MuscleNerd]