His place in history

    It's too early, of course, to judge the legacy of Bill Gates. He's only 52. His kids aren't even out of elementary school. And he has only just stepped away from Microsoft, a company that once put IBM in its place, and which some would say is the most significant company to come along since General Electric (GE, Fortune 500).

    Nor do we really know what - or even whether - Gates thinks of his place in history. As outgoing Gates Foundation CEO Patty Stonesifer puts it, "The Gateses by nature believe that the unexamined life is the one that's worth living. They don't like to talk about themselves. It's all about rational responsibility, not grand idealism."

    Buffett, who knows him as well as anyone, says the notoriously competitive Gates will have to find new ways to judge his accomplishments rather than by market share or in dollars. "He'll be competing with his own standards," Buffett says. "In the end, he is going to want people to look at the Gates Foundation 100 years from now and say, 'This guy did it the way it should have been done.'"

    With all he did at Microsoft, Gates has a tough act to follow. "Bringing personal computing to billions has totally changed the world, and it's changed it, net-net, way for the better," says Myhrvold. "So even before you look at what his foundation has done for Africa or for the poor, he's already done more for the good of the world than essentially anyone else in our lifetimes."

    Melinda Gates isn't at all surprised by Bill's transformation from feared empire builder to enlightened philanthropist. "I think the foundation, because it's not all about business and competition, allows other dimensions of Bill's personality to come out," she says. "He's incredibly funny and has an unbelievably wry sense of humor. He also can be very emotional when he sees the pathetic living conditions of so many people. He's a genuinely nice guy. I think more of what I see at home and what we see inside the foundation will come out. That will be a really nice thing for him and for the world."

    To which her husband would likely say, "That's the stupidest thing I've ever heard in my life."

    Just kidding.