Blackra1n: Jailbreak for iPhone OS 3.1.2
Currently the jailbreak software is only available to Windows users. It works on all generations of the iPhone and iPod touch, although the 3rd gen iPod touch needs to be tethered.
On his blog, Geohot wrote:
So, what is blackra1n? blackra1n is a 30 second ALL device 3.1.2 jailbreak. Even the ipt3, but the ipt3 is tethered. In order to boot it, just rerun blackra1n.
Warning 3g and 3gs unlockers, do not upgrade to 3.1.2 using iTunes if you want to keep your unlock. Baseband cannot be downgraded. Check out the dev team’s offerings. Also blackra1n doesn’t hacktivate.
iClarified created a post dedicated on how to jailbreak your iPhone using Blackra1n but also gave a warning:
WARNING: Even though the GeoHot jailbreak supports 3.1.2 do not update if you are on iPhone OS 3.0.1 or 3.0. You will lose your unlock. Use PwnageTool to safely update to 3.1 without performing a baseband update. If you really must have 3.1.2 then wait for the next version of PwnageTool. If you have already updated to 3.1 or 3.1.2 without using PwnageTool then you’ve lost the ability to unlock for the time being. You can now use BlackRa1n to at least regain your jailbreak 🙂