It's true, the Pac10 reversed their decision about allowing the megaphones, which as a matter of fact, I'm happy about as now we can at least show you how much sound we can put out with any other gimmicks.
From my contacts in the Athletics department, the decision was reversed because as an opposing team, Tennessee has the right to file a complaint about noisemakers (much like how LSU had a chance to complain about the cowbells on Thursday for a penalty) and I believe that is what caused the Pac10 to take another look at what exactly constitutes a noise maker.