Blackra1n Jailbreaks Apple iPhone OS 3.1.2
Apple updated the iPhone OS last week with iPhone OS 3.1.2 to fix some issues encountered by some iPhone users. If you are an iPhone jailbreaker than you can install the update and use the latest Blackra1n tool to jailbreak 3.2.1.
If you are actually want to unlock or keep your unlock than than you should not upgrade to 3.1.2 using iTunes. If you do the baseband is upgraded and no known unlock hack will work in the future.
Read more: i4u.com