BlackSn00000w is coming down, on me… Geohot, creator of the original iPhone unlock, has crack the 05.11.07 baseband to enable tethering, jailbreak for 3.1.2, and complete SIM unlock of the 3GS. This means you can use your iPhone on any GSM network.
To unlock:
1. First jailbreak your phone with BlackRa1n and then run the BlackRa1n app on the iPhone.
2. Later today you’ll see blacksn0w (it will appear in the BlackRa1n app). This app will unlock the phone completely.
3. Profit!
The jailbreak works under Windows and OS X. The unlock only works for 3GS models.