Christina Aguilera Photo by: Arnold Turner / WireImage.
Caught in the Act! | Christina Aguilera
• Christina Aguilera, singing "Happy Birthday" to husband Jordan Bratman (who turned 29 on June 4) at an MTV Movie Awards afterparty she hosted with pal Jessica Alba at Brent Bolthouse and Sam Nazarian's Hollywood hot spot Privilege. The singer even gave her man a special shout-out, saying, "I love you, baby." Also on hand: Kirsten Dunst, Jamie Foxx, Hayden Christensen, Nick Cannon and Courtney Love.

And party girl Paris Hilton threw a post-awards bash at her Hollywood Hills home. Zach Braff and Mandy Moore lounged by the pool and American Idol star Taylor Hicks chatted with Dancing with the Stars' Stacy Keibler. Meanwhile, down the hill, Eva Mendes, Brandon Routh, Kevin Spacey and Famke Janssen celebrated the big night with a fete at Hollywood's Chateau Marmont hotel.

• Justin Timberlake and Cameron Diaz, cuddling, kissing and dirty-dancing in the VIP area of Hollywood club Shag. Michelle Rodriguez hung out with friends in a nearby booth.

• Mariah Carey, proclaiming "Mariah's in the house!" over the deejay's microphone at Sean "Diddy" Combs's CFDA Awards afterparty at New York City club Pink Elephant. The diva wore sunglasses and had a glass of champagne in her hand at all times. Also in the house: Chloe Sevigny, Zac Posen, Tommy Hilfiger and John Legend. The Grammy winner cozied up to a pretty brunette companion, who indulged him in a lap dance. The duo left hand-in-hand at 2:30 a.m.

Janet Jackson Photo by: Gustavo Caballero / Getty
Caught in the Act!| Janet Jackson
• Janet Jackson, treating her entourage (including her backup dancers and four bodyguards) to dinner on the orchid garden terrace at South Beach restaurant Barton G. The singer, who's dropped more than 50 lbs., had sauteed mushrooms (cooked without butter) and chicken seasoned with lemon juice and olive oil (hold the potatoes au gratin). While in town, Jackson and beau Jermaine Dupri also partied at hot spot Mansion. At one point, DJ AM started spinning Michael Jackson's "Wanna Be Startin' Somethin'" and Janet got up and danced with pals.

• Ashton Kutcher, walking with his record label exec pal Guy Oseary in L.A.'s Runyon Park. The Punk'd star sported a mustache and wore red basketball shorts and a white T-shirt.

• Jennifer Lopez, dining with a female friend at Macaluso's on Miami Beach. She feasted on meatballs with fresh ricotta, homemade sausage and rigatoni with escarole and beans. After her meal, she went into the kitchen to meet owner Michael D'Andrea and his kitchen staff and posed for photos.

• By MARY MARGARET ACOYMO, MARGI BLASH, LESLEY MESSER, BRENDA RODRIGUEZ, LINDA TRISCHITTA and JON WARECH