At the moment, an unlock is in the works (Musclenerd made a tweet about it yesterday), but as of yet, there is no unofficial unlock available. When it's done, you'll need to update Cydia sources to include
http://repo666.ultrasn0w.com and after it's added, search in cydia for "Ultrasn0w". You'll need to make sure that your baseband is one that is supported (To find yours, go into settings -> about and it will be listed as Modem Firmware. You can follow Musclenerd for the latest news here:
https://twitter.com/#!/MuscleNerd