None of the songs on Guitar Hero: Smash Hits will be a surprise, since they're all songs that appeared on previous, guitar-only titles in the series. But still. You need to know what they are.
Activision have today released a partial tracklist, showcasing 12 of the songs that will feature in the game. Since none of them are Helmet's Unsung or Stevie Ray Vaughan's Texas Flood, I have grave fears for this title, but in the interests of fairness, maybe they'll be revealed later.
Guitar Hero
— "Killer Queen" - Queen
— "I Love Rock N Roll" - Joan Jett and The Blackhearts
— "Bark At The Moon" - Ozzy Osbourne
Guitar Hero II
— "Them Bones" - Alice in Chains
— "Killing in the Name" - Rage Against The Machine
— "Message In A Bottle" - The Police
— "Carry On Wayward Son" - Kansas
— "Free Bird" - Lynyrd Skynyrd
Guitar Hero Encore: Rocks the 80s
— "I Wanna Rock" - Twisted Sister
— "Nothin But A Good Time" - Poison
Guitar Hero III: Legends of Rock
— "Barracuda" - Heart
— "Through the Fire and Flames" - DragonForce