From ModMyi - Wiki

This tutorial won't unlock your iPhone 3G! To follow this tutorial, you must have the following:

1. Latest version of iTunes 2. QuickPwn 1.1 for Mac OSX 3. Firmware 2.1

Here are all the steps you need to follow:

1. Download all the files mentioned above.

2. Extract the QuickPwn disk image to get QuickPwn Tool.

3. Open iTunes and after your iPhone is detected, select your phone.

4. After that, press the option key on keyboard and click check for update.

5. Then select the firmware file you downloaded and select open.

6. iTunes will start the updating process.

7. Once your phone is updated, it will reboot.

8. Open QuickPwn, it will show a pop-up to connect your phone. Connect the phone and click OK.

9. QuickPwn will then ask you if you want to replace the boot logo (Boot: Pineapple and Restore: Cartoon Steve). Click yes or no.

10. QuickPwn will start the building the ipsw.

11. It will then ask you for your mac username and password. Type them and click OK.

12. When the process is complete, the DFU helper will start.

First of all, turn off your phone.

13. Then when asked, press home and power button for 10 seconds.

14. After that, release the power button and keep pressing home button for 10 seconds.

15. The phone will now enter DFU Mode.

16. After that, it will do send some files to your phone. Let it do it's work and do not interrupt.

17. After sending all the files, it will show you a success message and will tell you that now the pwning process will take place on phone. You can now close QuickPwn.

18. During the pwning process, your phone's screen will show some messages. Do not interrupt.

19 When the phone reboots, it will be jailbroken and unlocked!

All credits go to DevTeam for their wonderful work!