Headlining the weekend of August 5-7 will be Eminem, Foo Fighters, Coldplay and Muse.
Other notable additions (among many) include A Perfect Circle, My Morning Jacket, Deadmau5, Ween, The Cars (!), Arctic Monkeys, Death from Above 1979, Explosions in the Sky, Deftones (who are listed MUCH MUCH TOO LOW on the bill), Manchester Orchestra, Cage the Elephant, and Damian Marley & Nas.
Of course there are a ton of other acts on the bill. Click here to check out the full lineup.
My comments on the lineup: a bit heavy in the "bands that played both Coachella and Outside Lands" department, but there are also enough notable artists who avoided the other festivals to make Lollapalooza worth the money.
Ticket information and event details are available here on Lolla's official site.