Apple's yearly developer conference should see iOS 8, OS X 10.10, and likely some hardware.
"Off Contract" AT&T iPhone 4Ss Already Come Unlocked
The finding was noted by 9to5Mac and had also been discussed in the MacRumors forums where multiple users noticed that iTunes informed them of the "Congratulations your iPhone has been unlocked" message from iTunes:
I really have no idea. Part of me thinks it was some kind of glitch. The only thing I can think of is that a paid full price and didn't extend my contract. I ordered through Apple too. I wish there was a way I could confirm it, but I don't have any T Mobile or foreign sims laying around lol - BFW122083
The same thing appeared on mine when I did a restore... I am wondering if it came like this from the factory because I paid the full $849.99 for a 64 GB because my AT&T contract was not eligible for an upgrade...- mjcxpThe common thread was that they were purchased as off contract devices. Developer @stroughtonsmith has since verified this by purchasing one himself.
Meanwhile, it seems Sprint iPhone 4Ss are also come GSM unlocked according to @gruber who was able to successfully use a Canadian SIM card in his Sprint iPhone 4S. However, Sprint has promised to lock them at a later date.