The singer suits up as a police officer on the Harlem, N.Y., set of her new video. Plus: Pete Wentz, Kanye West, Britney Spears and more


Enjoying a few laughs, U.S. Open champ Serena Williams finds a fast friend in Tyra Banks Thursday at the Calvin Klein spring 2009 runway show during New York Fashion Week.

See all your favorite stars at Fashion Week.