Conversation so far:
What celebrities has Oprah Winfrey interviewed?
Winfrey hosted a rare prime-time interview with Michael Jackson, which became the fourth most-watched event in American television history.
Who else has she interviewed?
Winfrey appeared on the Late Show with David Letterman.
When did she appear on the late show?
On December 1, 2005.
Did she appear on his show more then once?
On September 10, 2007, Letterman made his first appearance on The Oprah Winfrey Show, as its season premiere was filmed in New York City.
Did she do any other high profile interviews?
Although Obama appeared twice on her show, those appearances were prior to his declaring himself a candidate.
Winfrey.

Question: Did she ever interview a president after they were elected?
Self-contained rewrite: Did Oprah Winfrey ever interview a president after the election?