Ooh la la-palooza exploded into a purple disco bacchanal tonight as Lady Gaga made her long-awaited appearance on stage (actually, for the second time today — the pop firebrand stunned the crowd by showing up to play drums briefly for glam-rockers Semi-Precious Weapons, the opening act on her Monster Ball tour). She then kissed band leader Justin Tranter while crowd-surfing. (Video here — you ain't going to see Taylor Swift do this).


Gaga — a very different artist from the little-known performer who appeared at Lollapalooza three years ago — staged a mini-version of her traveling tour production, providing Lollapalooza attendees with a sprawling set of hits, many of them played on a piano inside a smoking, rusted-out green car. See her stunning return to Grant Park in the pics (and then see more at Buzznet).