The Oscar After-Parties!

John Mayer and Jennifer Aniston

The night's big winners and the just-happy-to-be-nominateds alike were in the mood to celebrate a great night in film after the closing credits rolled on the 81st annual Academy Awards. Kate Winslet, Victoria Beckham, Penelope Cruz and Robert Pattinson all hit post-show bashes to mark the grand finale of awards season. After making a stealth entrance to the ceremony at the Kodak Theatre, John Mayer (in Salvatore Ferragamo) and Jennifer Aniston (wearing a Valentino Couture gown and Ferragamo clutch) engaged in a few public displays of affection at the Vanity Fair Oscar after-party, held at the Sunset Tower Hotel.

-With reporting by Brantley Bardin, Lindzi Scharf and Andrea Simpson

Jake Gyllenhaal and Reese Witherspoon

After presenting Slumdog Millionaire helmer Danny Boyle with the Academy Award for Best Director, Reese Witherspoon (in Rodarte) grabbed boyfriend Jake Gyllenhaal (in Ferragamo) and headed to the Vanity Fair bash. The couple chatted with Uma Thurman and nominee Amy Adams at the rooftop bash, where carb-deprived guests had their pick of guilty pleasure foods like In-N-Out burgers and brownies.

Eva Longoria Parker and Victoria Beckham

Less than a week after presenting her latest collection to key fashion industry insiders at New York Fashion Week, Victoria Beckham modeled one of her own designs at the 17th Annual Elton John AIDS Foundation Oscar party, held at the Pacific Design Center. In addition to watching the show, Beckham and fellow guests like Eva Longoria Parker helped raise funds for the foundation during a live auction and hit the dance floor when Sir Elton himself took the stage to perform a few of his classic tunes.

Jessica Biel

After paying tribute to the winners of the technical Oscars, Jessica Biel swapped her Prada column gown for a vibrant Oscar de la Renta dress before hitting the 1st Annual Party With A Purpose after-party at L.A. landmark Mr. Chow. "It's really a wonderful thing to be able to enjoy the glamour, have fun, have a glass of champagne, and then also look and see what people are really doing in their communities, in their lives and their worlds," said Biel, who encouraged guests to give to their favorite charities through her Make the Difference Network.

Freida Pinto and Dev Patel

"This is all a dream," said an incredulous Freida Pinto, who posed with Slumdog Millionaire co-stars Ashutosh Lobo Gajiwala, Ayush Mahesh Khededar, Azhar Mohammed Ismail, Dev Patel and Tanvi Ganesh Lonkar during the Fox Searchlight party at One Sunset. While Pinto glittered in John Galliano and Patel looked dapper in Burberry, Lonkar was a little lady in Vera Wang.

Jessica Alba, Halle Berry and Kate Bosworth

Best Actress co-presenter Halle Berry (in Marchesa) was among the most popular guests at the Vanity Fair bash, chatting with Russell Simmons, Vanessa Hudgens and fellow leading ladies Jessica Alba (in RM by Roland Mouret) and Kate Bosworth (in Alexander McQueen).

Madonna

Before heading out to host her own exclusive after-party with Demi Moore, Madonna (in Dior) was dripping in Neil Lane diamonds at the Vanity Fair bash. The Material Girl layered millions of dollars in platinum and diamond chains, cuffs and earrings over her little black dress.

Randy Jackson, Carrie Underwood and Ryan Seacrest

Chatting with Randy Jackson and Ryan Seacrest at the Elton John AIDS Foundation party, Carrie Underwood showed off her post-American Idol style in a Swarovski crystal and pearl embellished Georges Chakra dress straight from the runway in Paris. "It wasn't a long gown, but it was still nice and respectable," said the country music queen. "And it blings! It blings and I love it!"

Penelope Cruz

Though later in the evening, Penelope Cruz-who changed into a Versace evening dress before heading out to the parties-let Ashton Kutcher and Sean Combs pose for pictures with her Oscar at the Madonna/Demi Moore bash, the Best Supporting Actress winner kept a close watch on her trophy at the Vanity Fair soiree. What did the actress say in Spanish during her acceptance speech? "I said, I wanted to dedicate it to all the actors of my country and that I wanted to dedicate it to all the people that are now watching their in homes in Spain and that I am feeling that this award also belongs to them," Cruz explained.

Robert Pattinson

After hanging out with Zac Efron and Vanessa Hudgens at the Governor's Ball, Twilight star Robert Pattinson (in Dolce & Gabbana) smoothed out his famous locks before heading in to the Vanity Fair party. "I'm really classy!" declared the British actor, who passed up the champagne in favor of a beer.

Len Wiseman, Gwen Stefani, Kate Beckinsale and Gavin Rossdale

Gwen Stefani

(in Chanel) and Kate Beckinsale (in J. Mendel) posed with their handsome husbands, Len Wiseman and Gavin Rossdale, during the Vanity Fair viewing dinner, where guests watched all the action on large TV screens while dining on steak frites and chicken pot pies. After the broadcast Hollywood couples Sarah Jessica Parker and Matthew Broderick and Nicole Kidman and Keith Urban headed over to the Sunset Tower Hotel to join in on the fun.

Chace Crawford and Sir Elton John

Chace Crawford

-in an Emporio Armani (Product) RED tuxedo, sales of which benefit the Global Fund to help eliminate AIDS in Africa-was among the first celebrities to arrive at Sir Elton John's party. But while the Gossip guy was excited for his first big Oscar viewing party, John joked about the long night ahead. "[I'm looking forward to] leaving at the end of the night," the music icon deadpanned when asked about what was in store for his guests.

Anne Hathaway, Zac Efron and Vanessa Hudgens

Anne Hathaway

(in Armani Prive) fueld up on mini-cheeseburgers at the Governor's Ball before striking out to hit the other after-parties around town. "I think this was the best, most fun, most authentic Oscars in years," said Hathaway, who chatted with Zac Efron and Vanessa Hudgens (in Marchesa) about their respective musical numbers with host Hugh Jackman.

Kate Winslet and Meryl Streep

There were no hard feelings between Best Actress winner Kate Winslet (in Yves Saint Laurent) and nominee Meryl Streep-who already has two Oscars of her own-(in Alberta Ferretti) at the Vanity Fair party. The evening was a family affair for Kate, who formed an impromptu conga line with husband Sam Mendes and her father when it came time to take her leave.

Alicia Keys, Vanessa Hudgens and Halle Berry

Vanessa Hudgens

left Zac Efron for a few moments to go engage in a little girl talk with Alicia Keys and Halle Berry. "It was just incredible to be up there singing and looking out at all those incredible people," said Hudgens, when asked what was going through her mind as she hit the stage at the Kodak Theatre for a muscial number with her boyfriend, Beyonce and host Hugh Jackman. "[I was] like, 'I'm singing to Meryl Streep!'"

Hilary Duff

Hilary Duff

(in an Herve Leger skirt and Jimmy Choo strappy stilettos) brought along her mom as her date for the Party With a Purpose viewing dinner and after-party. In between offering applause for Oscar winners-"She's so cute!" Duff exclaimed when Penelope Cruz won the first award of the night-the actress chatted with fellow guests like Mario Lopez over Mr. Chow lettuce wraps. After the ceremony, crooner Michael Buble gave the crowd a surprise serenade.