Perry Farrell's sonic extravaganza, now in its twelfth year, is underway in Chicago's expansive Grant Park. Nestled amid the city's skyscrapers and boasting a musically diverse lineup -- as evidenced by headliners Radiohead, Nine Inch Nails and Kanye West -- the three-day event is sure to be a vibrant visual spectacle. So keep it here all weekend for pics of all the hot festival action.

At Pearl Jam's Lollapalooza-closing set, frontman and grunge icon Eddie Vedder said there was a "deep amount of meaning" for him to play in Chicago's Grant Park, given the amount of time that, as a kid, he would take the "El train" -- the city's subway -- while listening to his walkman. It was a meaningful Pearl Jam show for many other reasons as well: the performance was the band's only U.S. date this year, it was the fifteenth anniversary of when PJ first toured with the festival during its first incarnation as a multi-city, one-night-only summer shed touring production and, of course, the politics.

In matching purple tuxedos, My Morning Jacket opened their Day Three Lollapalooza performance with what was sure to be a unique set -- even for them -- with crowd pleasures 'What a Wonderful Man' and 'Off the Record,' the latter of which went into its customary jam as the entire Chicago Youth Symphony took their seats on the stage. But they weren't the only guests. Perry Farrell joined MMJ, asking the crowd, "Are we dreaming?" as he took the stage. The festival's founder then asked the crowd to take out their cell phones and cameras to record the show, "to make sure this isn't a dream." As if that weren't instruction enough, Farrell revealed that the audience should submit their footage to Current TV, to be compiled into a video for the band at a later date.

"Where's 'Ed Ved?" !!! frontman Nic Offer asked, extending a mock invitation to the Pearl Jam frontman to join the band during their Day Three Lollapalooza performance. The band played on, launching into 'Must Be the Moon,' a single from the octet's 'Myth Takes' albu. mAfter pontificating on whether or not Eddie Vedder's and Perry Farrell's parents ever called them "Ed Ved" or "Per Far," respectively, Offer thanked Farrell for the festival. "He had a dream and he realized it," he said. "What the f*** have you done?" His only complaint for Farrell: "You could've done better with the parking."

Performing with Pearl Jam last Thursday on the eve of Lollapalooza, and later headlining Day One with his own Innocent Criminals, the award for Most Dedicated Performer goes to Ben Harper. Need more evidence? On Day Three, Harper performed two songs solo on the kids' stage after flying to Baltimore on Day Two to perform at the Virgin Festival. Speaking to Spinner backstage, Harper admitted that his hectic weekend left him no time for his avid skateboarding hobby. Adding insult to injury, a few of his Pearl Jam buddies went skating over the weekend.

"Hello, motherf***ers! We are the f***ing Stooges!" an extra-psyched Iggy Pop screamed from the stage during the punk legends' Day Three Lollapalooza performance. Pop, who declared his excitement at playing "Lollapopapalooza," took the stage shirtless and with more piss and vinegar than most of the frontmen one-third his age at the festival, and launched into 'I Wanna Be Your Dog.' With his infamous crazy-eyed glare, Pop asked the crowd if anyone was thirsty. Not that he really cared, mind you. The eccentric frontman then doused himself with a bottle of water and chucked one at the audience -- not to help, but just for kicks.

Perry Farrell, addressing the kids at the Kidapalooza stage on Day Three of Lollapalooza, plugged his band Satellite Party in hopes of gaining a next generation of fans. Fronting School of Rock with Peter Distefano of Porno for Pyros, Farrell led the kids through a rendition of 'Summertime Rolls,' from Jane's Addiction's classic album, 'Nothing's Shocking.' And while the young ones in the crowd didn't know the song, the mom's and dad's knew every word.

On Saturday, My Morning Jacket's Jim James played banjo on the Kidapalooza stage, opting for something the kids would recognize: 'The Rainbow Connection' and the Chipmunks' 'The Chipmunk Song (Christmas Don't Be Late).'

Just minutes into their Saturday night headlining Lollapalooza set, Interpol was -- once again -- being considered "the next Joy Division." The band opened with a trio of tunes from their acclaimed sophomore album, 'Antics,' including 'Slow Hands,' before busting into the debut of 'Rest My Chemistry.' Frontman Paul Banks kept banter to a minimum, thanking the audience for "being here," and from there, Interpol offered up 'There's No I in Threesome' and 'Heinrich Maneuver,' both from their latest album, 'Our Love to Admire.'

Regina Spektor completed the trifecta of U.S. summer festivals Saturday with her Day Two Lollapalooza performance. But while her Coachella and Bonnaroo sets went off fairly hitch-free, this one suffered a minor hiccup through no fault of her own.

Before her show during Lollapalooza's Day Two, Rock & Roll Hall of Famer Patti Smith expressed her excitement for playing in Chicago -- the city of her birth. Her excitement was so much that she suffered a minor flub during the conclusion of her show opener, 'Redondo Beach,' from the classic 1975 album, 'Horses.' By the second song, however, Smith settled into the commanding presence she's maintained for more than thirty years -- just in time for the downpour that ensued. But Punk Rock's Poet Laureate and her band were impervious to the elements, as were her diehard fans. "We have to find a way to appreciate it," Smith said.

The Yeah Yeah Yeahs got their ya ya's out during their AT&T main stage performance on Day Two of Lollapalooza. Singer Karen O donned a silver mask, which pulled double duty: makeup protection from the light, steady rain and, of course, aesthetics. The mask was temporary, however, while the ya ya's were not as the band rocked the massive audience with a bevy of crowd favorites including 'Date With the Night,' 'Gold Lion' and 'Cheated Hearts,' as well as 'Down Boy' and 'Kiss Kiss,' new tunes from the band's recently released EP, 'Is Is.'

"Alright, Chicago! F*** yeah!" a black leather-clad Karen O yelled, smiling and relentlessly laughing her way through the YYYs set. "This is a love song," she said, "and I just wanted to say that I hope all of you had some summer loving!" The exuberant frontwoman then dedicated 'Maps' to the entire crowd, saying, "We know a thing or two about love."

A much-anticipated set by CSS was cancelled when the band failed to show for their Day Two Lollapalooza slot due to travel difficulties. A similar scene almost happened to Tokyo Police Club when the band's van broke down in Tennessee yesterday, en route to Chicago for today's main stage set. The band explained to Spinner backstage that the vehicle was in such bad shape, after a group meeting, they decided to ditch the van entirely, handing over the title for free to a stoked local.

"Welcome to Eddie's brithday party! We're the Hold Steady," frontman Craig Finn said, giving the b-day shout-out to the band's soundman before opening their Day Two Lollapalooza set with 'Stuck Between Stations.' At the Hold Steady's Lolla set last year, Finn proclaimed that it was "the most fun he's ever had before 3 o'clock." At precisely 5:43 pm today, he speculated that he was having more fun than he's ever had in his "entire life." Introducing the tune 'Hot Soft Light,' Finn explained that the song was about getting busted. The time of your life indeed, Mr. Finn.

"We'd like to play a love song about war, and a war song about love," Clap Your Hands Say Yeah frontman Alex Ounsworth said during the band's Day Two Lollapalooza performance, introducing 'Details From the War.' Two days earlier, at a festival pre-party thrown by Paste magazine and Guitar Hero, Ounsworth was forced to perform the same song -- as well as other Clap songs -- solo while his band was "stuck in New York City."

Just one day after surprising the city of Chicago with a secret show on the eve of Lollapalooza, Pearl Jam frontman Eddie Vedder had yet another surprise in store. "I'm going to bring out an old friend of mine," Ben Harper said during his Day One performance. "You'll know who he is when you see him." Without any further ado, Vedder took the stage and the two festival vets jammed together on a cover Bob Dylan's 'Masters of War.'