H'wood Party Girl

No valet, no red carpet and a Hilton sister wearing flip-flops? We must be at the T-Mobile Sidekick Tone Def after-party in Coachella Valley.

The music festival's famous fans, like Paris Hilton, Jared Leto, Sienna Miller and more, braved the dusty desert to hit the T-Mobile bash Saturday night, held at an airport hangar and lasting into the early hours of the a.m.

Paris spent most of her night with b-f Benji Madden and Nicky (who was sporting flip-flops). Hilton bro Barron was also spotted hanging at their table.

Meanwhile, Carmen Electra stayed glued to her new fiancé, Rob Patterson, and dished that they haven't set a date yet.

Sienna, who'd spent the day at the music fest, didn't even show up until around 2 a.m. She brought her parents along to the soiree, and they hung at their VIP table until 3:30!

In between his sets deejaying, Danny Masterson hit the PlayStation SingStar lounge to croon some karaoke. Partygoers with makeup meltdowns could also treat themselves to touch-ups from Too Faced cosmetics, engrave their cell phones or silkscreen T-shirts.

Besides the typical full bar, there were kegs of beer and frozen margarita machines for thirsty revelers. But plain old ice water was also a popular option—seems stars know hydration is key when you're partying in the desert.