Jessica Simpson-John Mayer reportedly over before it started

As rumors swirled last week that he was dating pop star Jessica Simpson, rocker John Mayer posted a message on his Web site that featured the cover art for Public Enemy's Don't Believe the Hype. Now Us Weekly reports that Mayer and Simpson's brief tryst is over, with Mayer being a bit scared off by the publicity the news generated and worried that Simpson was using him to promote her new album. One person in the Mayer camp told Us Weekly that the relationship "was a 2 [that] her camp spun into an 11.... [Mayer] thinks it's desperate...an attempt to stay in the spotlight."

Ashlee reportedly leaves guitarist for Fall Out Boy

Jessica isn't the only Simpson whose love life fascinates the gossip mags. Us Weekly reports today that Ashlee Simpson has left her guitarist boyfriend Braxton Olita for Fall Out Boy bassist Pete Wentz. Simpson's reps confirmed the split to the mag, which cites an anonymous source as saying, "Ashlee has been telling everyone that she's over Braxton," adding that Wentz recently dumped his girlfriend, Buffy the Vampire Slayer actress Michelle Trachtenberg. Simpson, 21, was reportedly seen partying with Wentz in the VIP section of a New York City club Saturday night.

Stefani plans line of dolls

Following in the tradition of the Spice Girls, Gwen Stefani plans to release her own line of dolls based on different looks that the singer and her Harajuku Girl dancers sported during her previous world tour. The series of limited-edition dolls are dubbed Love. Angel. Music. Baby. Fashion Dolls. "The Harajuku Girls and I wore such wicked costumes we had to share them with the world again," Stefani, 36, said in a statement. Each 10-inch doll will come with posters and trading cards and will sell for $24.95 at Target.com and other retailers.

Timberlake denies Diaz engagement

With Justin Timberlake in media blitz mode to promote his new album, FutureSex/LoveSounds, he's been getting deluged with questions about his relationship with actress Cameron Diaz. In an appearance on the Ellen DeGeneres Show, Timberlake performed in Central Park and afterwards was asked by the host repeatedly about the rumors that the couple are engaged. Timberlake tried to sidestep the questions, but eventually said, "We're not engaged."

He then added jokingly, "She hasn't given me a ring. I've waited for her to get down on one knee and ask." FutureSex/LoveSounds hits stores September 12, and the first single off the album, "SexyBack," is the top-selling song in the US, largely driven by digital download sales.

Diddy and girlfriend expecting twins

Just two weeks after confirming that his longtime girlfriend is pregnant, a spokeswoman for Sean "Diddy" Combs said today that the couple is expecting twins. Diddy and girlfriend Kim Porter have an 8-year-old son together, Christian, while Combs has a 12-year-old son, Justin, from a previous relationship with stylist Misa Hylton-Brim. Diddy unveiled the news in an "emergency announcement" video posted Monday on his Myspace.com page. The video was filmed on the front steps of his home, with Porter standing with him and Diddy saying, "Your boy is a champion! Two more Combs. Two! World, you're in trouble now." The couple learned of the double pregnancy during a recent trip to the doctor after Combs became concerned that Porter "looked kinda big for the amount of months she is." Diddy's new album, Press Play, hits stores in October.