For a change, I published 3 videos which definitely enables a total noob to unlock his/her iPhone without much difficulty. Latest Firmware via iTunes (2.2), QuickPwn (Jailbreak) and yellowsn0w via Cydia/installer (Unlock) hold the three key steps for a successful unlock.
Before proceeding further, make sure you are equipped with the following :
1) Strictly iPhone 3G Updated to 2.2 firmware via iTunes (2G iPhones have a different process – BootNeuter from Cydia).
2) Intel Mac (10.5.6 s/w update) or Windows machine. [Mac users, make sure DFU mode is enabled (10.5.6 s.w update and Unibod Macs have issues with iPhone not being recognized while Jailbreaking (QuickPwn).]
3) WiFi Network recommended. (If you don’t have a Wireless Router, try creating an Ad-Hoc WiFi network on your PC/Mac.
4) Make sure SIM Pin is disabled. Put your SIM in your old phone and disable the Pin.
If you are on the iPhone, click on the video title to watch it.