What it looks like it is Jelly Bean port to the Samsung Galaxy S III in real. Yes my fans, an XDA guy, has some success to port Google’s latest Android version, 4.1, on S III just one day after the search engine company announced the updated software.
The port has been achieved by the dev from Galaxy Nexus Jelly Bean OTA and the things like touchscreen, SMS, charging, physical buttons, and notifications LED worked just fine but Camera, Storage, Bluetooth, Audio, and NFC did not work as expected.
To put it in these words, it has been a semi-successful port, will be fair I guess. The dev behind this port is asking you all who can fix these errors so it becomes fully fledged Jelly Beaned S III.
Source: XDA Forum