from businessweek.com: David Letterman’s retirement from CBS next year may open the door for a woman to take over one of TV’s iconic late-night talk shows for the first time. Ellen DeGeneres would be an ideal choice, according to Mary Murphy, a senior lecturer at the University of Southern California’s Annenberg School for Communication and Journalism. Tina Fey and Amy Poehler would be good candidates, too, former NBC chief Bob Wright said today on Bloomberg TV. Letterman’s exit and the naming of a successor will complete a generational shift in late-night TV and give CBS the opportunity to make even bigger changes if the network is willing to gamble. It’s been more than 30 years since Joan Rivers became Johnny Carson’s regular guest host. Her efforts to start a competing show on Fox in the late 1980s faltered.