Sean Penn

Nicole Richie and Diane Kruger both went with black, but mixed it up with sheer panels and hot cutouts at the 2011 UNICEF ball at the Beverly Wilshire last night in LA. This weekend is a big one for Nicole, since she and Joel Madden will be celebrating their first wedding anniversary — check out Nicole's and Joel's cutest pictures through the years. Brooklyn Decker was sporting a glow, fresh from her Bahamas vacation with husband Andy Roddick last weekend. The model-turned-actress is also looking gorgeous in the first trailer for What to Expect When You're Expecting. Diane Kruger had her own tropical vacation recently: she spent Thanksgiving lounging in retro bikinis alongside hot boyfriend Joshua Jackson.

Sandra Bullock wore a sequined All Saints mini to attend last night's amfAR Inspiration Gala at LA's Chateau Marmont. She was joined on the black carpet by industry friends like her agent, Kevin Huvane. She shared space on the photo line with other leading ladies like Selma Blair and Garcelle Beauvais, and once inside, mingled with pals like Sean Penn and Colin Farrell, who brought his sister Claudine Farrell as his date. Kevin Huvane bought a Warhol painting for Sandra's son Louis during the evening's auction portion. Sandra joked about Kevin's buying Warhol's "Peaches" print for $14,000 while onstage addressing the crowd and paying tribute to Elizabeth Taylor. Sandra said, "I want to thank Kevin Huvane and Bryan Lourd for not being cheap f-cks and gifting my son with his first Warhol."

Sandra's back on the West Coast following a recent stay in NYC, where she joined best bud Ryan Reynolds to celebrate his 35th birthday. Ryan Reynolds brought girlfriend Blake Lively along for the bash at the club The Box, but the couple have now also left the Big Apple. Blake and Ryan are in Boston together, so he can continue working on R.I.P.D. with Jeff Bridges.

Producer Joel Silver gathered his famous friends in Malibu yesterday for a Memorial Day bash. Tom Cruise attended along with Katie Holmes, son Connor, and a high-heel-wearing Suri Cruise while Gwen Stefani and Gavin Rossdale turned out with their sons Kingston and Zuma. Guy Ritchie rolled up with his pregnant girlfriend Jacqui Ainsley, who could talk parenthood with a likewise expecting January Jones. The Mad Men star was just in NYC, where she showed off her upcoming blockbuster X-Men: First Class. A fresh-from-Paris Diane Kruger soaked up the sun with boyfriend Joshua Jackson while the holiday provided a chance for Courteney Cox and David Arquette to reunite with their daughter Coco. Celebrity babies were lucky to run on the sand between bouncy castles, and Minnie Driver's son Henry took advantage alongside Jennifer Meyer and Tobey Maguire's Ruby and Otis.

Gwen Stefani kept her Cannes Film Festival fashion coming this evening at the premiere of Sean Penn's This Must Be the Place, choosing a black-and-white gown with strategic cutouts. The singer went solo for the red-carpet debut after her husband, Gavin Rossdale, caught a flight out of nearby Nice this morning. Gavin and Gwen were together last night, though, for the amfAR Cinema Against AIDS fundraiser along with Kanye West, Bar Refaeli, and other stars. Sean was also by himself for today's unveiling of the film, without girlfriend Scarlett Johansson. Gwen's cycled through a collection of gorgeous gowns and dramatic outfits during her time on the French Riviera, but her trip hasn't been a completely formal affair — Gwen wore a bikini while enjoying the sun on a yacht with Gavin, Zuma, and Kingston this week.

Ryan Gosling popped up at his first Cannes event this evening looking dapper in Salvatore Ferragamo for the Cinema For Peace inaugural dinner honoring Sean Penn for his charitable efforts in Haiti. Leonardo DiCaprio and rumored flame Blake Lively took a break from lounging so he could stop by to say a few words while Robert De Niro, Naomi Campbell, and Uma Thurman sat in the audience. Ryan's arrival in France is later than most of the star-studded crowd as his upcoming flick Drive, costarring Carey Mulligan, is closing out the film festival. Carey debuted newly dyed brown hair this week in preparation for her next role starring opposite Leonardo in The Great Gatsby. The cast of the Baz Luhrmann remake of the classic is close to complete with Joel Edgerton now playing Tom Buchanan after Ben Affleck reportedly passed on the role last month. Carey's not the only link between Leo and Ryan, as Ryan was also momentarily romantically tied to Blake last Fall.

Bar Refaeli went casual last night to attend a party on Microsoft billionaire Paul Allen's yacht, docked off the coast of Cannes, alongside other stars at the film festival like Sean Penn and Zoe Saldana. The supermodel was just in jeans to attend the bash following a fancy few days. She wore a sequined Dolce and Gabbana mini to Monday night's Chopard party, then sizzled in a tight Roberto Cavalli number for the premiere of The Beaver yesterday. Bar's in the South of France despite any potential drama with her ex. Leonardo DiCaprio and Blake Lively seem to be getting cozy already, despite his breakup from Bar only making headlines last week. Bar admirably doesn't seem to be letting the split affect her social schedule, though she has been retweeting some inspirational quotes. The latest, from Robert Louis Stevenson, reads, "Don't judge each day by the harvest you reap, but by the seeds you plant."