The First Lady of television news, Barbara Walters has had an unparalleled 38-year on-camera reign, including 15 years as co-anchor of 20/20, nearly a quarter-century of top-rated specials, and exclusives with everyone from Fidel Castro to Muammar Qaddafi. At 67, making a reported $10 million a year and at the top of her game, she has nothing left to prove. As ABC's doyenne revels in the success of her new morning talk show, The View, and reels in the biggest "get" of her career—Monica Lewinsky— JENNET CONANT talks to friends, colleagues, and Walters herself about what makes Barbara the kind of tree that just keeps growing