Ashlee Simpson and Pete Wentz Photo by: Luisa Johns / Photokinetic; Tammie Arroyo / AFF-USA
Caught in the Act! | Ashlee Simpson
• Ashlee Simpson and Fall Out Boy's Pete Wentz, "glued together" at the hipster-magnet MisShapes party in New York City over Labor Day weekend. "They were making out," says a clubgoer. "Ashlee asked Jessica to take photos of her with Pete a million times." Our onlooker also says Simpson was downing shots and giving Wentz lap dances. And where was her boyfriend of at least eight months, bandmate Braxton Olita? "They decided to take a break," says her rep. "Ashlee is single. She is not dating anyone." Wentz's camp had no comment.

• Sienna Miller and Sarah Michelle Gellar, giving their waitress at Garden of Ono in New York City's Meatpacking District hairstyling tips. The two were there with a male friend, sipping vodka and cranberry drinks and munching on a dragon roll, tuna tartare and kobe beef skewers.

• Nicole Richie, lounging on top of pal Brody Jenner at Bungalow 8 in New York City – and reportedly getting into some "hot and heavy kissing" just before 3 a.m. in the club, a source tells us.

• Wilmer Valderrama and Lindsay Lohan, taking turns at karaoke at West Hollywood club Guy's. Valderrama got the crowd going with Oasis's "Wonderwall," but it was Lohan who brought down the house with Stevie Nicks's "Edge of Seventeen." "She had a lot of fun singing," says a source, but still, "she wasn't that great of a singer."

• Tony Parker, lunching with a pal – sans girlfriend Eva Longoria – at trendy L.A. Café Midi. Their conversation was tough to decipher, an onlooker said – the pals chatted in French.

• Lisa Kudrow, laughing as she dined with husband Michael Stern and friends at Asia de Cuba at the Mondrian hotel on L.A.'s Sunset Strip.

Nicole Kidman Photo by: BIG AUSTRALIA / Mike Emory / Andy Athineos / BEImages
Caught in the Act!| Ashlee Simpson, Nicole Kidman
• Sean Hayes and Ryan Gosling, each checking out the indie Sunset Junction Street Festival in L.A.'s trendy Silverlake area. While the Will & Grace star was there with a pal to see the Eels, the bearded Gosling raced to catch Black Rebel Motorcycle Club from under his newsboy cap.

• George Clooney, with a group of buddies, politely greeting the stream of fans (mostly women) who made their way toward him at the Stone Rose Lounge in L.A.'s Sofitel hotel.

• Nicole Kidman, eating Australian lobster tail at Vancouver's Morton’s the Steakhouse. The actress dined with her parents and two other guests, though husband Keith Urban was a no-show.

• By ALEXIS CHIU, MARK DAGOSTINO, SARAH PRESTON, MAUREEN HARRINGTON, KIMBERLY LANSING, MARISA LAUDADIO and JEFFREY SLONIM