Speaking to CNET UK, Samsung has confirmed the Galaxy S III sold abroad will be getting Android 4.1 (Jelly Bean) "as soon as" October. Which sounds wonderfully non-committal. Though if that October estimate holds true, it'd probably be a record for Samsung. Perhaps they've finally realized people care about OS updates.
We've already seen leaks of Jelly Bean firmware for the international S III, as well as the T-Mobile edition in the US, so this sounds about right to us. When the LTE version of the S III launches in the UK on the Everything Everywhere network, it will actually come with Android 4.1 pre-installed. The Galaxy Note II will launch with Jelly Bean as well, so we know Samsung's already been hard at work optimizing TouchWiz for the newest version of Android.
Timing for Jelly Bean on US versions of the device remains unknown. Given the aforementioned T-Mobile OTA leak, we're guessing Samsung is well on its way with the update. The fact that the hardware is identical across all four carriers will almost certainly speed up the process, too - and should mean relatively consistent timing regardless of your provider. In reality, though, we all know the dreaded carrier approval process will result in winners and losers in the race to update.
My money is on Verizon. For last place.