Now that Oprah Winfrey has ended her talk show we''ll look at her impact on culture, publishing and politics. Our guests include: Sheri Parks, associate professor of American Studies at the University of Maryland and author of Fierce Angels: The Strong Black Woman in American Life and Culture, Richard Sher, People Are Talking host and longtime Oprah colleague and friend, Kathleen Rooney, author of Reading With Oprah: The Book Club That Changed America and Craig Garthwaite, author of a study on the role of celebrity endorsements in politics: Oprah, Obama, and the 2008Democratic primary.