Android aficionados have something to celebrate this morning as a version of Android 4.3 has been spotted doing some testing rounds on Samsung's Galaxy S4. This early version of 4.3 is thanks to some porting work done by the fellows over at SamMobile.
SamMobile says that the port is fully functional on the standard Snapdragon-powered Galaxy S4 and there's not a single feature which isn't working. They know that the port is not flashable through Odin, it will void your warranty, and they only suggest attempting to install this version of Android 4.3 if you have the skills to flash custom ROM.
Even though Google hasn't made Android 4.3 public yet, you can head over to SamMobile (Source #2) and download the ROM now. Keep in mind that Android 4.3 is still in the development phase and currently cannot be considered 100 percent stable, so flash at your own risk and let us know how it turns out.