Not to be left behind by the larger carriers, US Cellular is also distributing the Android 4.3 update to the Galaxy S IIIs running on its network. In addition to the goodies that come with the latest version of Jelly Bean, this release gives Samsung's 2012 flagship the ability to pair with Galaxy Gear smartwatches, a privilege that until recently was exclusively provided to the Galaxy Note 3.
Galaxy S III users who do not own a Galaxy Gear may be more interested in the new Samsung KNOX compatibility or the improved pre-installed apps. The version number rolling out to devices is R530UVXUBMJA. You can manually check for the update if it hasn't already landed yet, but otherwise, just give it time.
A few days ago, US Cellular joined AT&T in halting the distribution of Android 4.3 to the Galaxy S4. That rollout remains on hold. So congratulations Galaxy S III owners, your update managed to come first.