An overjoyed Meryl Streep shared a laugh with Octavia Spencer as they had their Oscars® engraved at the Governor's Ball.
Best Actor Jean Dujardin gave his Oscar® a kiss and 82-year-old Christopher Plummer toasted his win as Best Supporting Actor.
The Governor's Ball was shimmering in purple and red with roses on every table when the stars arrived.
Waiters got their last-minute debriefing, with shrimp piled high on a buffet table as chocolate fountains flowed on another.
Over at the Vanity Fair party, Jennifer Lopez arrived with her 24-year-old dancer boyfriend Casper Smart but walked the red carpet alone in her second spectacular Zuhair Murad gown of the night which featured another plunging neckline.
She had to hold the dress in place to keep from popping out.
J.Lo was asked about the playful moment when she and Cameron Diaz aimed their posteriors at the Oscar® audience.
"We were just being playful, having some fun, trying to loosen the mood. Felt like a crowd that needed a bit of a jolt," Lopez told reporters.
Tonight Show host Jay Leno talked about that big moment before the Oscars® when comedian Sacha Baron Cohen arrived dressed as The Dictator and dumped fake ashes on Ryan Seacrest.
"There are real dictators causing controversy - one who threw ashes at Ryan Seacrest, somehow that is bigger than Libya in the show business world. I love it," said Leno.
At the Elton John party, supermodels Heidi Klum and Bar Rafieli did their own playful impression of Lopez and Diaz on stage antics.
Singer Katy Perry attended the party solo and was an enthusiastic bidder at an auction to benefit AIDS research.
At the Weinstein party, the French media mobbed Jean Dujardin as he walked the red carpet. Another star of The Artist who stopped the show was Uggie. The adorable Jack Russell terrier was decked out in a black tie.
Joel McHale, star of NBC's Community and E's The Soup praised Billy Crystal's hosting of the Oscars®.
"You feel taken care of, you feel he is going to guide this night," McHale told INSIDE EDITION.
Meanwhile, amid all the partying there was one sour note.
Actress Sean Young is now commenting about her battery arrest at 1:45 a.m. after she allegedly slapped a security guard outside the Governor's Ball.
"I basically moved my arm. I just kind of got him straight in the face and that is when they all went postal on me," Young told reporters on Monday.
The 52-year-old Young, who co-starred with Kevin Costner in 1987's No Way Out, was reportedly trying to get into the Governor's Ball without a ticket.