Star Tracks - Friday, August 31, 2007

While filming continues on What Happens in Vegas. . ., Cameron Diaz gets an unexpected break – a birthday treat! – as she celebrates her 35th while on set in New York on Thursday.

Britney Spears continues her string of giddy public appearances while grabbing a bite to eat in Beverly Hills on Thursday. The pop star seems primed for a career comeback after releasing the single "Gimme More" in advance of a new album that's due in stores Nov. 13.

He may have made a stylish entrance at the Venice Film Festival, but George Clooney is no match for his Michael Clayton costar Tilda Swinton when it comes to owning the red carpet before a screening of the movie on Friday.

Does Pink have a new groupie? The singer and John Cusack spend an friendly afternoon together on the streets of Berlin Thursday. While Pink is in town to perform, Cusack is filming the action movie Stopping Power in the German capital.

Nicole Richie gets an energy boost – thanks, Jamba Juice! – during a stroll through Beverly Hills on Thursday. The fruity snack is another healthy food choice for the five-months pregnant star.

Is it a case of bad reception? Paris Hilton gets über-expressive while waiting for her flight at Los Angeles International Airport on Thursday. The heiress is reportedly on her way to Frankfurt, Germany.

A well-dressed Carrie Underwood takes over downtown Los Angeles while filming a new music video on Thursday. The former American Idol, who recently released the single "So Small," has just announced the title of her sophomore album – Carnival Ride.

Prince Charles and his sons, Price Harry and Prince William, share a sober family moment outside London's Guards Chapel during Friday's memorial service for Princess Diana on the 10th anniversary of her death. Inside, Prince Harry recounted, "To us, just two loving children, she was the best mother in the world."

After visiting refugees and American troops in Iraq, Angelina Jolie follows Brad's lead and heads to Central Park on Thursday, getting hands-on with daughter Shiloh, 15 months, at the petting zoo.

Meanwhile, after his Big Apple day with daughter Zahara, Brad Pitt gets to work on the set of the new Coen brothers film, Burn After Reading, on Thursday.

Rihanna rides shotgun to racecar driver Jeff Gordon during the California Speedway's Running Wide Open event, a fund-raiser for the NASCAR Foundation, at Hollywood club Avalon on Wednesday.

Looking tanned and relaxed (his villa in Lake Como is less than 200 miles away), George Clooney arrives at the Hotel Cipriani on Giudecca Island in Venice on Thursday. The actor's film Michael Clayton will show in competition at the Venice Film Festival on Friday.

Gwyneth Paltrow pauses for a paparazzo while out shopping in New York's SoHo neighborhood on Wednesday. The actress was snapped leaving Kirna Zabête, a downtown boutique known for avant-garde fashion.

Following a trip to New York where her hotel room was burgled, Kirsten Dunst watches her back as she stops by the Whole Foods in West Hollywood on Wednesday.

Serena Williams takes time off from the U.S. Open to give a tennis lesson to pop star sisters Aly and AJ Michalka during a taping of MTV's TRL in New York's Times Square on Tuesday.

Listen to Aly amp AJ's