The long-running rumors about the big headliners (Radiohead, Nine Inch Nails, Rage Against The Machine, Wilco, Kanye West, Raconteurs) were all true. The full lineup is now available at the official website.
If you're too lazy to surf over there, here are some names that weren't on the list before:
Cat Power
Love & Rockets(!?)
The National
Explosions In The Sky
Gogol Bordello
Stephen Malkmus
Okkervil River