Finally! After our friends in Canada started getting Android 4.1 – Jelly Bean last night on their Galaxy S3, it looks like tonight AT&T has started pushing some Jelly Beans to their Galaxy S3 customers. Currently the update is available through Samsung's sort of crappy software Kies, it's also available to flash if you grab the file from Samsung-Updates. The build is I747UCDLK3. And the entire update is 691.4MB if you're planning to flash it. The OTA should be much smaller than that. Around 320MB is what users in Canada were getting last night. But that just shows how clunky Touchwiz is, since stock Android is around 170MB.
Users are reporting on both Reddit and XDA that Jelly Bean is officially available for the SGH-I747, a.k.a. the AT&T model. So far it's unclear as to whether or not the update is available via over-the-air update from AT&T yet. As no one has confirmed success from OTA updates yet.
This is a big update for your Galaxy S3, just in case the file size didn't already tell you that. It includes Google Now, Expandable notifications, Project Butter and more. Of course Samsung has updated their Touchwiz interface and added some bug fixes, which is normal for an update.
With this update the AT&T Galaxy S3 adds to the Sprint, T-Mobile, Canadian and International Galaxy S3's to get Android 4.1.1. Also the HTC One X (International), Motorola Droid Razr M, Motorola Droid Razr HD, and Motorola Droid Razr Maxx HD. All of which have gotten Jelly Bean updates in the past few weeks.
If you're able to get your update, let us know how you're liking it. If you're wanting to pull it down via OTA. Simply go into Settings, hit About Phone then hit System Updates and Check for updates. You may not be able to pull anything down until tomorrow or later. Also AT&T's updates are weird in that you can only check once in a certain length of time. Have fun with your Jelly Beans.