An anonymous source talking to GSMArena has stated that the update to Jelly Bean for Samsung Galaxy S III users will debut alongside the Galaxy Note II at Samsung's press conference on August 29. The fact an update is coming comes as no surprise to us as a few weeks ago information popped up about it being developed.
At that time, however, no release date was given and it was thought that it would launch late Q3 or early Q4. The anonymous tipster has said that the update is ready to go. Galaxy S II and Note owners will have to wait it a bit longer, if they will get it at all. Testing is currently on-going at the Korean smartphone giant.
The tests are reportedly "looking fine" but no date has been given for the release. Given strong international sales of both the Galaxy S II and Galaxy Note, it's somewhat unlikely that Samsung won't come through with an update. If they don't, there are plenty of hardware hackers on XDA-developers that will provide a ROM.