The world’s wealthiest man, Microsoft’s Bill; Gates has joined the board of an investment company owned by the world’s second wealthiest. SiliconValley.com reports that the board of billionaire Warren Buffett’s Berkshire Hathaway voted yesterday to elect Microsoft founder Bill Gates to fill the current vacancy left by July’s death of Buffett’s wife Susan. Gates has long been a shareholder in the company and is a friend of Buffett’s, with the two frequently playing bridge together.