Sidekick-loving stars piled into the Palladium in Hollywood this week to help T-Mobile launch the Sidekick III. Eva Longoria, The O.C.'s Rachel Bilson, former O.C.-er Mischa Barton, Nicole Richie, Paris Hilton, the Duff sisters (Haylie and Hilary) and a host of other stars checked out the newly-designed device that features a 20 percent size reduction, a trackball, and integrated Bluetooth technology, and watched the Futureheads and She Wants Revenge rock out on stage. The event space entertained celebs with topiary animals, light projections, real grass and trees, and a full playground.

Check out which celebs attended the ultra-exclusive event:

Former bandmates Mark Hoppus and Travis Barker with a friend

The sisters Duff: Haylie and Hilary

Eva Longoria leans on Jessica Simpson

The O.C.'s Rachel Bilson and Veronica Mars' Kristen Bell

Mischa Barton is just a touch taller than Nicole Richie

Paris Hilton with BFF of the moment, Kim Kardashian

The Futureheads' Barry Hyde

She Wants Revenge performs

Talk: Will you run out and buy the new Sidekick?

On the Web: sidekickiii.com