• Britney Spears, beginning a night of clubbing with mashed potatoes and chocolate cake at French brasserie Rue 57 before heading to Marquee, where she met up with old pal JC Chasez and danced in the deejay booth to Madonna’s “Vogue.” Next stop: hot spot Tenjune, where she partied with two girlfriends, a bodyguard and a male companion until 4 a.m. Her night on the town ended with a stop at McDonald’s for a late-night snack.

• Cameron Diaz, leaving West Hollywood’s Gym on Nemo Street after a workout. It was an Angelic day at the fitness center: Diaz’s Charlie’s Angels costar, Lucy Liu, also pumped iron there. If Drew Barrymore showed, the reunion would have been complete…

• Jennifer Aniston, dining with two female pals at Beverly Hills eatery Spago. On the table: Cantonese-style roasted duck. “They were having a terrific time,” an onlooker tells us.

• Ashlee Simpson, holding hands with a female pal as she made her way to the bathroom during rock band Ringside’s concert at the Roxy in West Hollywood. Also in the house to support Brothers & Sisters actor Balthazar Getty‘s group: His costar Dave Annable, who got cozy with Grey’s Anatomy star Kate Walsh, Eric Dane, Justin Chambers, David Arquette and newly single Cisco Adler.

• Kevin Federline, surrounded by five bodyguards and a large posse of more than 15 people at West Hollywood club Area. The sharp-dressed rapper, who wore a collared shirt and sport jacket, drank bottle-service cocktails and smoked cigarettes as he chatted with the ladies around him and partied with Wilmer Valderrama. Also making the scene: Jermaine Dupri, who stood on top of his VIP table, and Dane Cook, who hung out near the bar and talked to friends.

• Paris Hilton, looking at Hello Kitty and Strawberry Shortcake dolls at West Hollywood novelty store Aahs.

• Justin Timberlake, dancing at the Black Eyed Peas concert at Hollywood club Avalon. The Grammy nominee was content to play fan in the audience. When the band (with whom he collaborated on their hit 2003 song “Where Is The Love?”) invited him on stage, “he just laughed and continued having fun with his friends,” says a concertgoer.

• By KIMBERLY LANSING and SARA LIBBY

See Thursday’s Caught in the Act >

• Nicole Kidman, strolling through Beverly Hills. The actress stopped into an office building before emerging with her bodyguard and driving off in her car.

• Justin Timberlake, taking over the owner’s table at New York City club PM after his concert at Madison Square Garden, where he reunited with Andy Samberg to perform their infamous Saturday Night Live song “D— in a Box.” The singer – who celebrated at a Fashion Week party for celebrity stylist Phillip Bloch – came in with 20 friends and family, drank only water and danced to some of the songs guest deejay Nick Cannon played. Also making the scene: Diddy, Jamie-Lynn Sigler, Kelly Rowland and Cuba Gooding Jr.

• A brunette Jessica Simpson, playing photographer at L.A.’s Hyde Lounge during a night of partying with sister Ashlee, Eva Longoria and hairstylist pal Ken Paves. “They were having a ball,” an onlooker tells us about the singer, who was clad head-to-toe in black. “Jessica was snapping pictures of everyone with her digital camera.” Earlier in the evening, Simpson and Paves had dinner with friends at Beverly Hills restaurant Mr. Chow.

• Shakira, lunching on grilled Hawaiian prawns on a frisee lettuce salad at Italian eatery Il Cielo in Beverly Hills.

• Leonardo DiCaprio, hanging out with pal Kevin Connelly at Hollywood lounge Les Deux. It was a star-studded night at the Euro-style hot spot. A low-key Ryan Phillippe talked to a male friend, Prince spent the evening holed up in the private VIP area, Cee-Lo from Grammy-nominated group Gnarls Barkley held court as revelers showered him with compliments, while Scarlett Johansson chatted with girlfriends at Wilmer Valderrama‘s table nestled behind the deejay booth. “Scarlett was just really mellow,” says an observer. “There wasn’t anything romantic or whatever going on between her and Wilmer.”

• By KC BAKER, KIMBERLY LANSING and MARY MARGARET

See Wednesday’s Caught in the Act >• Kevin Federline, hanging out with male pals at a VIP table at L.A. club Privilege. “Despite the bevy of beauties enveloping his table, Kevin made time to send a long text message,” an observer tells us. On the table: Red Bull, orange juice and vodka.

• Demi Moore, Ashton Kutcher and Nicole Richie, celebrating at a belated birthday dinner for actress pal Sara Foster. Guests including Rebecca Romijn and Kevin Connelly feasted on filet mignon, penne pomodoro and three different kinds of cake from L.A. bakery Hansen’s Cakes.

• Pregnant Keri Russell, dining at Prana Cafe in L.A. The actress – who’s expecting her first child with fiancé Shane Deary this summer – sipped on an iced tea and lunched on a blackened chicken wrap.

• Heath Ledger, rocking out at a performance by San Francisco indie band Foreign Born at West Hollywood’s The Viper Room.

• By MARK DAGOSTINO, VANESSA DIAZ, KRISTEN MASCIA, BRENDA RODRIGUEZ and JEFFREY SLONIM

See Tuesday’s Caught in the Act >

• Reese Witherspoon, balancing a smoothie in one hand and a shopping bag in another while out in Beverly Hills. During her trip, the actress picked up some items from trendy shoe store Madison.

• Lindsay Lohan, hanging out with a female friend at hot spot Teddy’s at the Hollywood Roosevelt Hotel. “She was in a good mood, talking to her girlfriend the whole time,” says a fellow clubgoer about the “cute” Lohan, who was dressed in a layered ensemble. “She looked really comfortable on a plush leather couch.”

• Desperate Housewives Eva Longoria, Nicollette Sheridan, Teri Hatcher, Andrea Bowen and Brenda Strong, celebrating at a Cosmopolitan-hosted party for costar Felicity Huffman‘s book A Practical Handbook for the Boyfriend at hip L.A. story Iconology. The ladies reported that pregnant costar Marcia Cross – who was put on bed rest last month – is doing great. “I just talked to her for about three hours,” Longoria told us. “She’s hanging in there!” And Huffman said Cross (who’s due in April) will make an excellent mom. “She’s really big-hearted and really generous. She’s full of love and caring and compassion.”

• The O.C.‘s Adam Brody and Benjamin McKenzie, having a guys’ night out at L.A. bar The Dime. The newly single Brody and his costar kept to themselves – and didn’t chat with any ladies.

• Sienna Miller, chilling out near the pool table at the Gramercy Park Hotel. At one point, she left the lounge and smoked a cigarette with a muscular guy in the bar.

• John Legend and Destiny’s Child’s Michelle Williams and Kelly Rowland, polishing off sushi, short ribs and fudge cake at a Fashion Week party for designer Max Azria at New York City’s Buddha Bar.

• By SHANNON BRADLEY, VICTORIA BRETT and NATASHA BURTON

See Monday’s Caught in the Act: Super Bowl Edition >

Caught in the Act: Super Bowl Edition

• Nick Lachey and Vanessa Minnillo, dining at China Grill Saturday evening before moving on to South Beach’s hip lounge Mokai for the CAA Sports private function. With pal Matt Leinart in their entourage, the guys sipped beers and chatted while Minnillo chatted with her girlfriends. Other revelers included Super Bowl frolickersTom Cruise and Katie Holmes, Scarlett Johansson, Alec Baldwin,Heroes star Milo Ventimiglia, Fergie and Josh Duhamel, Yankees star Alex Rodriguez and his wife, John Legend and Gloria Estefan. Though they didn’t have any interaction, Lachey’s ex father-in-law Joe Simpson also was on hand. Lachey and Minnillo stayed until after 2 a.m., leaving hand-in-hand with six other pals.

• Jeremy Piven, dropping into Playboy‘s Eighth Annual Super Saturday Night party at the American Airlines Arena in downtown Miami. “It’s all about the game,” the Entourage star told us as he stood among the open bars and dozens of Playboy bunnies in white lingerie. “That’s why I’m here. It’s all about the Chicago Bears. I’m from Chicago.” Also showing team spirit: Jermaine Dupri and Taye Diggs.

• Ludacris, getting into the casino-themed swing of things at Maxim magazine’s Super Bowl party at the Sagamore Hotel’s Social Miami club on Friday night. The swanky hotel was transformed into the Hotel de Maxim, where guests downed Absolut cocktails and played with fake money at the Borgata Casino. Though many celebs – including Nick Lachey and Vanessa Minnillo – stayed holed up in the VIP area, David Spade and Ryan Cabrera mingled in the crowd.

• Mark Wahlberg, hosting his own private party at INK Boutique Nightclub in South Beach on Friday. “Kanye West is here, and I saw Pharrell out walking today,” Tampa Bay Buccaneers quarterback Chris Simms told us. “But I’m most excited to meet Mark Wahlberg. Extremely excited. He’s pretty big-time between (producing) Entourage and (starring in) The Departed. He’s extremely hot right now.” And the host was extremely flattered. “These guys want to meet me?” said Wahlberg, whose bash was benefiting his Youth Foundation. “That’s pretty cool. All I ever wanted to do was be a professional athlete, so to get that kind of love is very nice.”

• Jenny McCarthy, Carmen Electra and Kelly Monaco, hanging out with a group of 15 friends in a private skybox at the Snow Queen Vodka 4th Annual Leather and Lace party at Chakra Lounge Friday night. During the festivities, McCarthy stopped a photo mid-pose to answer a text message from boyfriend Jim Carrey.

• Venus Williams, bragging about sister Serena’s Australian Open win at the exclusive Bamboo Lounge at the ESPN Block Party Friday. “A lot of people thought she was going to lose, but she won,” she told us. As for the Super Bowl in Miami, “I’m a South Florida girl, I’m loving it here,” she said. Alyssa Milano showed up for the fete after flying in from L.A. The actress gushed about Indianapolis Colts quarterback – and Super Bowl MVP – Peyton Manning (“I met him once and he was a very nice guy,” she told us) and chatted about her new women’s baseball clothing line, which is set to be released on baseball’s opening day. “It bridges the gap between the game and the after-party,” she said.

• Kevin Federline, being surrounded by a horde of women at the Penthouse party at Mansion on Saturday night. It was a repeat visit for the rapper, who’d hung out there with producer Scott Storch the night before. Also checking out Snoop Dogg‘s performance at the Penthouse bash: Paris and Nicky Hilton, along with her beau David Katzenberg.

• Kid Rock, partying at Mokai and then hitting up the Red Room at Shore Club’s Skybar on Friday. He hung out with rapper Lil Jon until 4 a.m. and then moved over to Rok Bar with a blonde female friend.

• By KRISTIN HARMEL, CARLOS MILLER and JON WARECH

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