I love my Galaxy S II, but I really want to see what the next-gen Galaxy handset can do. The GT-i9300 has been spotted on Samsung's support page, but since it was spotted, has vanished.
Samsung's model numbers work very specifically, with the Galaxy S II being the GT-i9100, the Ice Cream Sandwich-powered Galaxy Nexus the GT-i9250, so the GT-i9300 would indicate that it should, not will, be the Galaxy S III.
I think we'll see an announcement soon, and a launch before the iPhone 5. Samsung can get a good head start and will make Apple salivating to release their next iOS-powered device. Hopefully the GSIII has Ice Cream Sandwich, and a higher-resolution display. Keep that sexy Super AMOLED screen please, Samsung.