AT&T has released an over-the-air update for Samsung Galaxy S II SGH-i777 users. This update mainly includes bug-fixes and bumps the Android version to 2.3.6 from the existing Android 2.3.4.
Update size is 20MB and you will soon get a notification to install the update. A few reports have suggested that if you have rooted your Galaxy SII, then chances are that your update will fail. So, if you really want the update, then you will have to unroot it, else wait for developers to figure something out.