Though it's far from perfect. And as with any leaked software, you download it at your own risk.
The leak was posted over at the XDA Developers forums, Android Police reports. If you want to run it on your T-Mobile Galaxy S3, you'll need to run the stock T-Mobile Ice Cream Sandwich ROM, aka T999UVALH2.
A version of Jelly Bean leaked last week, but that was restricted to US Galaxy S3 owners.
So what about these bugs then? Some brave early downloaders have reported losing. Others have said Wi-Fi calling doesn't work, and they've also reported bugs with the stock browser and video player. Worst of all, Google Now might not work -- which seems to miss the whole point of the download -- and there may be some issues in general performance.
Maybe just wait until the, eh?
Google Now knows where you are and what you're up to, and provides you with info relevant to your situation. So if you're setting out on your commute, it'll tell you train and bus times, traffic info, the weather, and more.
If you do take the plunge with this leaked update -- and again, I have to stress it's at your own risk -- let me know how you get on in the comments below, or on Facebook.