Just want to inform owners of iPhones locked to AT&T who are not yet aware of this news. I just tested it this morning and my iPhone 4 is now fully unlocked. I used to run Gevey SIM on it. Then my sister-in-law (who bought this for me in America) rang AT&T support yesterday and gave the IMEI and they told her they've unlocked it on 8th of April this year. I'm now using 5.1 and dumped my Gevey sim :D
Here's the newslink from Engadget
http://www.engadget.com/2012/04/09/att-now-unlocking-iphones/