US Cellular's variants of the Galaxy S III and Note II are slated to receive OTA updates to the MB1 build, which includes a bump to Android version 4.1.2 for the GS IIII (the previous Note II update here, previous GS III update here).
The Galaxy S III's release notes indicate only two changes: the aforementioned increase in OS version, and a fix for audio when playing streaming media (this may fix a long-reported issue with Netflix playback on the device).
Galaxy S III
Build JR003L.R530UVXMB1 - Android 4.1.2
Items updated, added, removed from the device:
- Android version Jelly Bean upgrade to v4.1.2
- Fixed audio issue with streaming media
The changes built into the Note II's update (build R950VXAMB1) are unknown, as it was already running Android 4.1.2.