Apple has instructed the The Apple Store employees if they run out of Unlocked iPhone they can sell AT&T units to the customers and System will automatically unlock those phones. Few weeks ago Apple Started selling unlocked phones in the US,For the Unlocked phones you will need to buy the contract free phone for 650USD for 16GB and 749USD for 32GB model. Earlier iPhones were locked and were exclusive to At&T carrier in the US and even if you paid full price and got it of contract, still you could only use the iPhone on At&T in the US.
It is a good thing as it gives the users to jump to any GSM carrier they want to if they not happy with the current one and it will also be a opportunity for many people to get the latest iPhone a year early from a country with the second largest population and one of the fastest growing economy in the World and which is the dumping ground for outdated iPhones. So if you have relatives in the US and you want the latest iPhone and it won’t come to your country anytime soon, you can just get it from there and you don’t even have to worry about different software and hardware ways to Unlock the phone.
This is all a leaked information and there is still no word if Apple or At&t will be willing to unlock the iPhone sold before Apple decided to sell unlocked phones, as there are many people who unlock their iPhone and use it on different carriers, In India the number of iPhone bought and brought from outside of India are actually more than than the iPhone sold and used in India as it’s a year late and comparatively expensive than other countries.