It's suppose to feature some kind of "drum component". There'll most likely be more info tomorrow during Sony's Press Conference (considering they'll be "revealing" the new PSP Go) at E3.
This makes, what, the 5TH Guitar Hero game to come out this year?
It's getting kinda ridiculous how many music games are coming out, flooding the market much? That said, I would not be surprised if Activision decided to do a 5-button music game, just to 1-up Harmonix and their 4 button Rock Band.