Well... from my understanding AT&T seems to be catching up with employees giving access to AT&T's database to unlockers. I know for a fact that unlocks can still be done... so it's not a server thing like some people here are saying. This is something else..
I pressume that AT&T has some sort utility that Apple provides to all carriers so they can unlock devices for their customers. I know that not all operators have access to this system.. only guys at the iPhone Tech Desk on AT&T. That utility probably requires be some login information. I think a few of the guys at that department decided to make an extra buck and granted open access to the entire thing and that's how AT&T unlocks got so widespread and cheap...
AT&T got tired of having all their phones unlocked by this method and probably patched up the loopholes allowing external access to their DB. The whole thing started about 5 days ago. All suppliers sent emails before the problem began announcing about some kind of update that would go on at AT&T. An employee who works there told me that day that the unlock system wasn't available.. next day the apocalipsis began.. probably unlockers noticed they had no more access to AT&T after the update and that's why everything is the way it is now..
Expect these services to increase in price by a lot.. I was selling them for US$1.25 on eBay and now my price is US$25... BTW I can do any iPhones from 5 and below.. 24 hours..