I have to agree with Ash, one New York band on the soundtrack doesn't mean anything in terms of location, and every other GTA is proof of that.
I wonder if Rockstar would really let this (or anything else) slip?
Then again, I remember things like the auditioning of voice actors for SA where we got the three character names: Madd Dogg, Maria & Maccer. And I think that was pre March 1st 2004. Also didn't Danny Dyer announce he was in SA well before we knew anything about it. *shrug*