iPhone users are probably aware of the tie-up between Apple and AT&T. This agreement has forced iPhone users to subscribe to AT&T's services or resort to unofficial means to unlocking the phone, a process more commonly known as jailbreaking.
The public has clamored and it has been heard. iPhone's Development Team has created an official unlock for iPhone 3G.
Link: How to Unlock your iPhone 3G - washingtonpost.com