Despite repeated on-air pleas, David Letterman probably won't be guesting on The Oprah Winfrey Show anytime soon. Or vice versa. Winfrey tells Time magazine that during her previous two appearances on Letterman's Late Show she was "sort of like the butt of his jokes. I felt completely uncomfortable sitting in that chair, and I vowed I would not ever put myself in that position again." I'm sure that whole "Uma, Oprah" debacle didn't help either.