At the moment everyone seems to be trying to shift there iPhone 5 stock as this comes not long after the deal that BestBuy are offering as they have slashed the iPhone 5 prices and it seems AT&T are following the pattern.
AT&T started a promotion that takes 50% off its entire smartphone lineup. That is all smartphones so even Android devices are included. According to 9to5Toys, the offer is valid for both the iPhone 5 and 4S and includes both free shipping and activation if purchased online. The deal shows up when you go to purchase the device.
Its not going to be a long promotion so be sure to get it while you can but with all the iPhone 5 deals starting up it would seem that Apple is telling them to shift iPhone 5 stock to make way for the 5S.