Sure, the Galaxy S III is the first major flagship device to get Jelly Bean outside the Nexus line. That's not fast enough for you, though, is it? Of course not! We can do better! Or, more accurately, XDA can do better. In fact, a TouchWiz Jelly Bean ROM has found its way to the development forum giant's threads already!
The build is still unofficial and obviously there are inherent risks to flashing it. Some users are reporting trouble with MMS, and as usual, root is not guaranteed to remain intact. Be sure to read through the thread before doing anything fancy with your phone. If you're feeling adventurous, though, head to the source link to find your downloads.