Additionally, two different track lists, one with 80 songs and another with 60 have also been uncovered, though how reliable they are is anyone's guess. There are some songs on both lists, and each list might contain future planned DLC that might never get released. The rumored lists after the jump.
Source -- 8bitfix
Source -- Loading Reality
Source -- Kotaku
[Update: According to IGN Xbox Team Editor-in-Chief Hilary Goldstein, "Nate (the originator of the above quote) goofed in writing that. He hopes that is allowed. Nothing about this has been announced and Nate's never even seen RB2. Sorry, guys." Guess we'll all find out the truth at E3 next week, huh?]
Source - IGN Boards (registration required)