Best Selling Samsung Galaxy S2 And Galaxy S3 will be rolling out for Android 4.1.2 in next few days, Since firmwares updates have now been leaked on internet. The Leaked firmware is quite stable, bugs-free and packed up with lots of new features. Surprisely leaked firmware includes Samsung multitasking implementation, Google Now, Project Butter, Smart Start and much more interesting stuff.
We are expecting maybe Samsung release an official updates in next month December.
Firmware update number I9300XXLSJ and Android build JZO54K, you can easily take look at source code link, if you are ready to get yours hand on it.
Source: Via XDA