Pop Tarts: Prince 'Uninvites' Lindsay; Petra and Penn; Kathy Hilton Goes Crazy on Barron

Just because the Academy Awards ceremony ended before 9 p.m. PT doesn't mean that Hollywood went to sleep. In fact, at least a dozen main streets in the area were blocked off to accommodate a slew of star-studded parties.

Jennifer Love Hewitt hosted a sweet soiree called "The Envelope Please" at The Abbey in West Hollywood. Dressed in dazzling white, a stunning yet super-slim Hewitt nibbled at the fine foods — let's hope the mean comments about her bikini bottom last year aren't still bothering her.

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Over in the lavishly lit Grand Ballroom of the Four Seasons Hotel for the Mercedes-Benz bender, Rick and Kathy Hilton drank and dined well into the evening, but were they babysitting their son, Barron, too?

While he isn't old enough to drink, the 18-year-old hotel heir — who recently was arrested on suspicion of drunken driving — apparently took time out to do something he is allowed to do ... have a smoke out in the back.

Pop Tarts has been told, however, that Kathy suddenly got super-cranky when she spotted her little one sipping what appeared to be a vodka tonic.

"She started to panic," said our spy, "but soon found out that it was only lime with ice water, so she was pretty relieved."

Britney's "cousin" Alli Sims also stopped by the classy celebration to pose for pics, causing several people to question if she honestly believes she is a true celebrity. Meanwhile, Stacy Keibler was seen in a private Beverly Hills home celebrating at the small Ariva/Marani Vodka event with a man all over her.

But the hottest (and hardest-to-get) tickets in town were invites to the Madonna and Prince bashes.

The Material Girl joined forces with Demi Moore to host an intimate affair for 200 in the beautiful Beverly Hills home of Maverick Music founder Guy Oseary.

Security that was tighter than at Fort Knox, however, wasn't the only incredible expense on the bash's bill. The digs were decorated by fountains upon fountains overflowing not with water, not with wine, but with the finest absinthe Le Tourment Vert. (Mind you, that is 75 percent alcohol and only just legal in the United States).

The A-list-only attendees included Tom Cruise and Katie Holmes; Ashton Kutcher and Moore; Ellen DeGeneres and Portia de Rossi; Diddy; Forest Whitaker; Cameron Diaz; Orlando Bloom; and an incredibly festive Javier Bardem, who was about the only one dancing by the turntables as everyone else mingled poolside.

However, our Madge showed her age by giving her guests the boot by the stroke of midnight — and giving them the go-ahead to attend Prince's "Citizens of Humanity" bash at Beverly Park.

Every single Oscar-winner except Daniel Day-Lewis was in attendance, getting down (and somewhat dirty) even after sunrise, along with the likes of John Legend, who apparently got super-friendly with Miss USA Rachel Smith; Christina Milian; Mia Maestro; Kate Beckinsale; Eva Longoria; and Oscar host Jon Stewart.

Despite Prince's reported promise to Elton John that he would perform at his party, the "Purple Rain" sensation bailed and only belted in the early hours with pals Stevie Wonder and John Legend.

"He didn't do Elton's because he wanted everyone who was anyone to come to his party and see him exclusively," an insider informed us. "Prince can be unpredictable."

Speaking of unpredictable, Tarts has been told that Sean Penn and model Petra Nemcova were "all over each other all night long," getting cozy while Penelope Cruz hung out (and made out) with Javier Bardem, who changed into sneakers and jeans while showing off his Oscar to everyone in sight.

"It was a total love fest," an insider said. "Penn and Petra totally looked like they should have gotten a room. Sweet but sickly." Penn and Nemcova reportedly said they are just friends.

Meanwhile, Orlando Bloom and Rumer Willis reportedly arrived together and acted very "couple-like." According to our all-night spies, Bloom and Willis didn't leave each other's side all night as they whispered and wooed over mac n' cheese while on the corner couch. Wasn't it just last week that the romantic relationship between Bloom and Victoria's Secret "Angel" Miranda Kerr went public?

Pop Tarts was left wondering where on earth party girl Lindsay Lohan was amid the excitement.

"A big deal was made by Prince's people that she wasn't to be invited or if she was already, she needed to be uninvited," our source said. "Apparently, Lindsay thought they were friends, so I am assuming she would have been disappointed."

'Simple' Sister-in-Laws: Paris and Nicole?

We always knew they were best buds since childhood, but it seems "Simple Life" starlets Paris Hilton and Nicole Richie are about to get closer as double-daters.

Rumors of a romance between Hilton and Good Charlotte rocker Benji Madden have been bubbling for a few weeks now, but the two were "openly together" over the weekend as Paris partied and Benji turned the tables at a party in Missouri. (Funny that Hilton decided to stay away from Hollywood on its hottest party weekend, especially after rumors ran rampant last week that she was banned from Elton John's bash.)

Her pal Richie is engaged to and just had a baby with Benji's bro Joel Madden. You never know, those two reality girls could someday be sister-in-laws!

Speaking of engagements, it wasn't so long ago that Benji was engaged to Aussie pop princess/actress Sophie Monk. (In fact, both girls look oddly alike with their blond hair, blue eyes, tans and tiny frames).

Although Monk repeatedly denied that she and her rocker were on the rocks (despite her being spotted several times without her ring), Pop Tarts did spot her dining last week at Nobu in Beverly Hills with a mystery man. Go girl!

Pre-Oscar Partiers Given the Boot

A slew of stars and starlets stepped out on Saturday evening to toast the eve of the Academy Awards at Hollywood's hottest hotspot, GOA; however, the drinks and dancing were cut short not long after midnight when the music suddenly stopped and the lights came on to expose the overpacked place.

The LAPD and fire-marshal friends put a prompt end to the party, as GOA apparently broke its occupancy clause, forcing the Paris and Lindsay wannabes of the world out into the pouring rain.

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