NEW YORK, HOLLYWOOD, CHICAGO & BEYOND... -- Thursday, November 6 in LA: Hayden Panettiere, Nicole Richie, Drew Barrymore, Heidi Klum, Donald Sutherland, Lucy Liu, Fergie and Ryan Seacrest, among many more, watched Madonna perform with Britney and later Justin Timberlake at Dodger Stadium... Emilio Estevez, who just signed on for a guest appearance on "Two And A Half Men" sitting in the foyer Thursday mid-morning at Shutters Hotel in Santa Monica....

In San Francisco: Ashton Kutcher and MC Hammer celebrated MySpace Music's recent content channel launch, with a party featuring a performance by R&B legend Lionel Richie, who sang his classic hits, including "All Night Long" and "Brick House -- DJ AM also performed...

The rest of this week's celebrity sightings inside!

Wearing a subtle white blouse and black baggy pants, Britney joined Madonna on stage to sing the last verse of the track "Human Nature," much to the delight of the packed house, which included some serious star power - Jennifer Lopez, Ryan Seacrest, Heidi Klum, Drew Barrymore, Nicole Richie and Fergie.