Brad's Dinner Date: Madonna

01/27/2006 at 06:00 AM EST

Being fashionably late isn't Brad Pitt's style. So the actor was the first to arrive for a dinner with pals Madonna, Guy Ritchie and celebrity chef Jamie Oliver at London's Locanda Locatelli recently. But his arrival was anything but low-key: When he showed up at 8:30 p.m., it "turned the restaurant on its head," says chef and owner Giorgio Locatelli about the mob scene his entrance created among the eatery's female diners.

Once he settled in, Pitt – whose pregnant girlfriend Angelina Jolie wasn't feeling well and stayed behind at Claridge's Hotel with her kids – lounged for several hours with his pals at the trendy Italian restaurant. They finally ended their evening together at 12:30 a.m. and declined an offer by the restaurant's management to be escorted out the back door and through a garage.

Caught in the Act: Sundance

• Cameron Diaz (right), sporting a sparkler on her left ring finger while shopping at The North Face House. "She was wearing a big ring – a bunch of diamonds intertwined," says an observer. The actress tried on several pairs of jeans at the Lee Jeans suite but wanted to get beau Justin Timberlake's opinion first. Earlier, the two went straight from snowboarding to pick up a $35,000 pair of diamond and platinum Nefarious sunglasses at the SkiHouse at The Canyons.

Jennifer Aniston, chowing down at the invite-only dinner ChefDance, hosted by the Food Network's Tyler Florence. She feasted on tuna parfait with two kinds of caviar, Alaskan butterfish and champagne lychee gelee, all prepared by Ming Tsai of Boston's Blue Ginger restaurant. When Tsai asked Aniston how she was enjoying his food, she responded, "It's insane."

• Scarlett Johansson and Josh Hartnett, dancing together at the Motorola Late Night Lounge party. Other celeb couples making the scene were Paris Hilton and beau Stavros Niarchos; Rob Thomas and wife Marisol; and Sting and his missus, Trudie Styler.

• By ALEXIS CHIU, LISA INGRASSIA and MARK DAGOSTINO