Couples Watch: Naomi & Liev, Nick & Mariah

• Naomi Watts, stepping out for a night at the theater with Liev Schreiber. The parents-to-be (again) attended the opening of Broadway’s Speed-the-Plow at New York’s Ethel Barrymore Theatre.

• Mariah Carey, sharing a musical reunion with husband Nick Cannon at the Delano Hotel in Miami after spending the evening apart. The couple had fun singing Journey’s “Don’t Stop Believin'” and “were so cute,” an onlooker tells us. Cannon had been working for the night – deejaying at a BlackBerry party at hot spot Prive – while Carey and her small entourage enjoyed their time off, sipping pinot grigio at The Florida Room inside the Delano.

• Ryan Phillippe and girlfriend Abbie Cornish, sharing a romantic dinner at Nobu Los Angeles. The couple sat tucked away and, according to a fellow diner, were “very low-key,” though Phillippe “seemed very doting.” Across the restaurant, Victoria and David Beckham dined with a small group of friends.

• Lauren Conrad, arriving at Teddy’s inside the Hollywood Roosevelt Hotel hand-in-hand with Kyle Howard. The pair strolled to their back table at their favorite L.A. haunt after midnight, and weren’t hiding their PDA. They were constantly holding hands as they danced and mingled with their friends. Later, the two ventured out to the smoking patio where they held hands some more and even kissed a little in between conversations with the Hills star’s girlfriends.

• A very pregnant Lisa Bonet, brunching at Axe in Venice Beach, Calif., with boyfriend Jason Momoa and their 15-month-old daughter, Lola. Wearing a flowing white dress and floppy black hat, Bonet had the pancakes (as did her beau) at a corner table while Lola stayed in her stroller next to Dad. The Life on Mars star looked relaxed and radiant.

• Elton John, celebrating husband David Furnish‘s birthday at Las Vegas’s Hard Rock Hotel & Casino‘s pool. The pair partied at the Palapa hut with celeb pals including Gina Gershon, and when the party ended, the revelers left the hotel, piling into private buses and limos.

• Johnathon Schaech, celebrating the release of his horror film Quarantine at TAO Las Vegas with the movie’s producers and girlfriend Jana Kramer, who had just arrived from Los Angeles. The group sat by the restaurant’s signature buddha statue, and enjoyed their dinner before heading upstairs to continue their festivities.

• Chelsea Handler, hanging close to boyfriend Ted Harbert at the GREEN FOR GOOD Women’s Health cocktail party by the pool at L.A.’s Sunset Tower Hotel. The comedian was hosting the event (along with Lake Bell), and happily chatted with her boyfriend and some female friends, gossiping and laughing over cocktails. Harbert brought his girlfriend drinks from the bar and stood next to her all night.

• By ALEXIS CHIU, JENNIFER GARCIA, MARK GRAY, BRETT MALEC and LINDA MARX

Friday’s Caught in the Act >