Controversial biographer Kitty Kelly is planning a tell-all, unauthorized book on Oprah. "Oprah Winfrey has fascinated me for many years - as a woman, she has wielded an unprecedented amount of influence over the American culture and psyche," Kelley said last week in a statement. "She has built an empire around her personality and has been one of America's most admired businesswomen and philanthropists. Oprah's story is one of hope, promise and realization of the American dream." The title and publication date of the book have not been announced. Kelley has a history of penning notorious tell-alls, and her previous subjects have included the Bush family, Nancy Reagan and Frank Sinatra. According to the publisher, Kelley "plans to interview hundreds of sources, many of whom have never before spoken on record about her subject."