Parties! The style, stars and scoop from Hollywood's hottest events

"Hi, I'm Mariah and I'll be your hostess for the night!" announced songbird Mariah Carey, who got revelers like music producer—and Janet Jackson's significant other—Jermaine Dupri (right) into the spirit of the evening at Benny Medina's birthday bash. After Carey wheeled out the guest of honor's Moroccan-inspired cake, Medina surveyed the room and declared himself "the happiest man in the world."