Katie Couric celebrated her 55th birthday Saturday night with a party at the Bowery Hotel. A newly single Couric, who we revealed recently split with her young boyfriend Brooks Perlin after five years together, looked radiant in a black Michael Kors cocktail dress, according to fellow guests. Couric was toasted by friends, including Michael J. Fox, Hoda Kotb, Rosanna Scotto, Bob and Lee Woodruff, Jeff Zucker, CBS News’ Byron Pitts and former ABC News chief David Westin before she took to the dance floor. Couric’s syndicated daytime show starts in September and will appear on ABC in New York.