This makes no sense to me. The Lego Star Wars, awesome, Indiana Jones, okay, but Rock Band, Lame!!! I don't want to see my favorite rocker lego'd out, the coolest part about those other lego games was how the environment broke apart like legos and how the guys would fall apart, what will they do in Rock Band? It'll probably be a huge hit though.
I don't get it either. it's this king of cash-cowing crap that the rock band community bashes activision and the guitar hero crew for. but nooooooo, when the RB guys do it they aren't milking it at all.....*cough*RB-Beatles*cough*
It's just a way to appeal to younger audiences. Some parents might be reluctant to get music games with songs like Down With the Sickness and Chop Suey. But if it has a friendly Lego face it will be all right. I'm still not sure if it is worth it's own game. If has a decent setlist with a good amount of songs it will just be a good track pack.