About a month after Sprint users were treated to the same, owners of the LG Optimus G on AT&T are starting to see their update to Jelly Bean. The software upgrade brings the phone to Android version 4.1.2 and includes features like Google Now and expandable notifications.
To see if the update is available for your Optimus G, head to the About Phone menu under settings and check for new software. If ready, you should receive necessary Android 4.1.2 upgrade files over-the-air.
[Thanks to those who sent this in!]