Samsung and carriers did a decent job last year of upgrading almost every Galaxy S3 out there to Android 4.1 Jelly Bean. Still, as Google plows ahead with Android development, what can you expect next as a Galaxy S3 owner? The answer is Android 4.2.
International and U.S. Galaxy S3s are pretty much all running Android 4.1.1 or Android 4.1.2 at this point. Premium Suite has been rolled out to most Galaxy S3s, giving them the ability to use Multi-Window just like the Galaxy Note 2. Google rolled out Android 4.2 for its Nexus lineup late in 2012, and the update will the natural next step forward for the Galaxy S3.
Early reports and rumors indicate that the Galaxy S3 will start receiving Android 4.2 in Q1 2013. This, as usual, applies mostly to international and unlocked variants. Those with carrier-tied Galaxy S3s will have to wait longer as the network approves the upgrade for distribution. This is old news for those of us in the United States, and especially for those on Verizon's network.
Android 4.2 will bring some welcome additions to the Android operating system's repertoire. Multiple users will be able to create their own accounts on the same phone that can be accessed and customized much like a normal desktop would be shared among family members or friends. A new mode called Photosphere allows for panoramic pictures, and Google Now has been improved. The usual bug fixes apply.
If you're tired of waiting for official updates, and are feeling adventurous, you can pick up Cyanogen Android 4.2 ROMS. They are still in early phases, so they won't be as stable as the official release, but if you really must experience Android 4.2 on the Galaxy S3, it's one of your best options. Just be sure to back up your device before flashing.