Nope, no DLC or added content for Music Studio has been announced or even hinted at for the future.
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Guitar Hero III-NYC Champion as of 10/31/07
I like Rap AND Metal. They're similar in many ways. Wanna fight about it?
Proud Muslim.
"I asked this guy, 'Come on man, dinosaur fossils, what's the deal? He goes 'God put those here to test our faith'."
"I think God put you here to test MY faith, dude".
-Bill Hicks