Arturito.net

The whole process is pretty simple.
Requirements:
1.    iTunes 7.5
http://www.oldapps.com/itunes.htm
2.    iPhone firmware 1.1.4
http://appldnld.apple.com.edgesuite.net/content.info.apple.com/iPhone/061-4313.20080226.Sw39i/iPhone1,1_1.1.4_4A102_Restore.ipsw
3.    ZiPhone
http://files.ziphone.org/ZiPhoneWin-3.0.exe
4.    iBrick
http://www.iphone-hacks.com/downloads/file/37
This tutorial will guide you through unlocking iPhone to any sim, activation and jailbreak.
First of all you will need to downgrade your iPhone from version 2.0 to 1.1.4.
1. Uninstall iTunes
2. Reboot the computer
3. Install iTunes 7.5
4. Connect your iPhone to the PC.
5. ITunes might tell you that you require version 7.7 , don’t worry about it and click OK.

6. Now, switch iPhone to DFU mode. NOT Recovery mode. In DFU mode the screen will be black. In Recovery Mode it shows cable and iTunes icon.  You can simply follow this video on YouTube showing how to put iPhone in DFU mode. http://www.youtube.com/watch?v=fiTcKMZfyfk

7. iTunes should detect your iPhone now.  Press and hold SHIFT and click Restore. Select Firmware 1.1.4 file that you have downloaded before. iPhone will take around 10-15 minutes with replacing firmware.
8. When done.  Launch iBrick program and select to restart iPhone. If the background colour on iPhone will change to red it means that you have done something wrong. You should try again. If it goes green, it means that everything went well and your iPhone will reboot to normal mode.

9. Launch ZiPhone program and simply click on Do It ALL. The program will start to upload some files to the iPhone and it will reboot it. You will see the shell console and the task the program id performing. The process takes less than 10 minutes.

Enjoy your iPhone.