Hollywood Celebrates a New 'Sidekick'

Young Hollywood came out Tuesday night to celebrate the official unveiling of a new generation of the T-Mobile Sidekick -- the sleek new Sidekick 3 -- and ET was there to catch all the excitement!

NICOLE RICHIE, JESSICA SIMPSON, RACHEL BILSON, MISCHA BARTON and PARIS HILTON are all gearing up for summer and got the party started right with their fellow thesps in a fun, unique setting!

Former friends and "Simple Life" co-stars Nicole and Paris were careful to stay on opposite sides of the red carpet, while the stylish heiress, looking like she just stepped off of a yacht, filled ET in on her fashion, saying she was in love with the "sailor look."

Paris' summer plans include a big promotion for her new album: "I leave Thursday for London and perform there, then all around Europe, Paris [and] Germany."

Meanwhile. Jessica Simpson spent the evening running around with pal EVA LONGORIA, who told ET her beau TONY PARKER was at home glued to the NBC championships!

Richie's on-again-off-again man DJ AM spun tunes for the crowd, who partied in the ultimate dream world: the theme of the night was childhood memories -- the grown-up version! Partygoers got to frolic through a playground landscape complete with slides, swings, a sandbox, trees, real rolling grassy hills and twinkling lights and floating bubbles overhead. There was also a boardwalk of carnival games with prizes, photo booths and more.

The evening's event also gave back to kids by donating old Sidekicks and any wireless devices for the T-Mobile "Get More, Give More" recycling program. Proceeds from the recycling program benefit the "T-Mobile Huddle Up" community outreach program, which helps kids from single-parent families in high-need, urban communities connect to positive people, places and programs.