While the American Scream 3 site is not even up yet, the German site seems to be the only place to find anything. A message has recently been posted at www.Scream3.de, the Official German website for Scream 3. It reads..
Ab mitte August bieten wir hier regelmäßige Neuigkeiten rund um Scream3. Also schauen Sie wieder rein, es lohnt sich!
The very cool Christopher Nelson (the guy who tipped me off about the message) says that it says something to the effect of on August 15th, the Official German site will have more info on Scream 3.