Dev Team has released 3G Unlock. The unlock works on any 3G iPhone! We will have a complete guide step by step for all those who are not sure on how to do this.

Note:

• To perform the Unlock your iPhone 3G must be Jailbroken -  Tutorial Here
• Your device must be on 04.26.08 baseband [Firmware 3.0]

Here

But it is fairly Simple – :

1. Ensure you have upgraded to iPhone OS 3.0
2. Jailbreak your iPhone 3G using redsn0w or PwnageTool (this will also install Cydia/Icy)
3. Run Cydia or Icy
4. Please add the repo repo666.ultrasn0w.com to Cydia or Icy. That last “o” is actually the number zero “0”! If you use the letter “o” you’ll get an error.
5. Search for ‘ultrasn0w’ in cydia or icy and install ultrasn0w
6. Reboot your iPhone 3G
7. T-Mobile USA users should disable 3G before using ultrasn0w
8. Enjoy

Like always many thanks to Dev – Team for their work.