The Guitar Hero Community forums confirmed songs and artists for Guitar Hero: World Tour.

Steve Miller Band - The Joker
Interpol - Obstacle 1
The Doors - Light My Fire
Linkin Park - In The End
Michael Jackson - Beat It
Smashing Pumpkins - Bullet With Butterfly Wings

Confirmed artists, songs unkown:
Nirvana
Muse
Beastie Boys
Van Halen
Foo Fighters