Android 4.1 Jelly Bean Now Available for Galaxy S3 on AT&T
This is not an over-the-air (OTA) update, at least not yet. According to posts on Reddit, Jelly Bean is available on Samsung's Kies software (free download).
"I can confirm this. Downloading it right now. For those who have never connected their S III to their PC on Kies via USB, you first need to download it on your PC. Then connect your device when it asks you to. Make sure your battery life is fully charged and it'll say that there's a new firmware upgrade. Click to upgrade to Jelly Bean," Reddit user "QuestionAxer" posted.
There aren't a whole lot of details since AT&T hasn't posted a Galaxy S III specific changelog or anything of that nature, though all the standard features of Jelly Bean -- like Google Now and improved notifications -- will be there.