Gayle King , Oprah Winfrey's best friend, has moved into a penthouse purchased in the name of Oprah's recently departed pooch, Sophie. According to deed-transfer records released yesterday, a company called Sophie's Penthouse LLC bought a $7.1 million full-floor sky palace atop the 36-floor building at 207 E. 57th St., reports The Post's Braden Keil. It has three bedrooms, 31/2 baths, a large living room/dining area, and a 768-square-foot wraparound terrace. Note to my friends, step up your game.