EXCLUSIVE: Read it here first...

Nicole and Joel's Friday Night with Mariah and Prince

Mon., Jan. 28, 2008 4:08 PM PST by Marc Malkin

In what may have been their first night out since becoming parents earlier this month, Nicole Richie and Joel Madden hit megamanager Benny Medina’s 50th birthday party on Friday night.

The couple was among the 200 or so who filled Medina’s Hollywood Hills home for the splashy shindig. Mariah Carey flew into L.A. just for the bash and gave a toast, before helping present Medina with his birthday cake, sources tell me.

Prince, I’m told, showed up late in the night and was quickly escorted to the second floor of the house, where Carey retreated after the cake was served.

Ashley Olsen spent most of her time chain-smoking. Also there were Paris Hilton, Nicky Hilton, David Katzenberg, Mischa Barton, Kevin Connolly, Cuba Gooding Jr., model Karolina Kurkova and director Brett Ratner. “The theme was Casablanca Fly,” one guest reports. “It was ‘40s-inspired decor, and you had to dress to impress.”

Richie and Madden were joined at the bash by her dad, Lionel. Papa Richie arrived after performing at the Beverly Hills Hotel during a party for Dr. Phil’s 1000th episode.

Earlier in the day, the talk-show therapist taped the episode that included an hourlong chat with Oprah Winfrey about their early days working together, an audience member tells me.

Winfrey toasted Dr. Phil with some champagne. However, she didn’t make it to the after-party and Richie concert because, I’m told, she had to get on a plane to South Carolina for some Barack Obama campaigning.