Over the weekend XDA forum member freeza posted information about a leaked build of Sprint’s pending Android 4.1.1 Jelly Bean update for Samsung Galaxy S III devices. The leaked ROM includes Samsung’s custom TouchWiz interface. Unfortunately, it also includes a few items not quite working right like the stock browser, Google Now and some issues with the device’s gyroscope sensor. Nevertheless, it is clear that build JRO03L is close to complete, which means we may see it rolling out to users soon.
If you are not willing to wait for Sprint to make it available and you can live with the issues, you can hit the source link to pull down the leaked file or one of the custom ROMs the XDA community has already generated. Trying out any of these is subject to the usual warnings about messing up your device.
For those content to wait for the update via Sprint, hopefully this leak may help create some pressure for Samsung and Sprint to accelerate their schedule a bit.
source: XDA Developer Forum