Buffett is famously uninterested in modern technology, although he does use a computer to play online bridge with his friend Bill Gates and others.
Gates tweeted back, "Welcome to Twitter @WarrenBuffett. First ever Twitter bridge tourney starts now. I bid 3 Hearts." He included a link to a photo of the two playing a hand.
While people in Buffett's office use e-mail, he doesn't have a computer on his desk.
He has been using a cellphone for several years, but missed what could have been an important call during the Lehman Brothers collapse because he didn't know how to check his voice mail.
In his Fortune editorial, Buffett writes that one of the reasons he's so optimistic about America's future is that women are beginning to reach their full potential.
"Fellow males, get onboard. The closer that America comes to fully employing the talents of all its citizens, the greater its output of goods and services will be. We've seen what can be accomplished when we use 50% of our human capacity. If you visualize what 100% can do, you'll join me as an unbridled optimist about America's future."