Apparently iPhone users can now jailbreak the iPhone 3.1.2 firmware with the aid of the blackra1n software which has now gone live reports an article over on daily mobile.
Word is blackra1n is a thirty second iPhone 3.1.2 jailbreak that works on all iPhone devices and even the ipt3, however the ipt3 is tethered. Although currently blackra1n is for Windows only but a Mac version is expected in the near future.
To boot it all you need to do is rerun blackra1n and as usual if you jailbreak your iPhone do not update the iPhone firmware via iTunes.