Steve Ballmer was sobbing. He repeatedly tried to speak and couldn't get the words out. Minutes passed as he tried to regain his composure. But the audience of 130 of Microsoft's senior leaders waited patiently, many of them crying too. They knew that the CEO was choked up because this executive retreat was the last ever for company co-founder Bill Gates, as well as for Jeff Raikes, one of the company's longest-tenured executives. "I've spent more time with these two human beings than with anyone else in my life," Ballmer finally said. "Bill and Jeff have been my North Star and kept me going. Now I'm going to count on all of you to be there for me."

　　What the executives were witnessing was the end of an era. On July 1, Gates officially retires from daily duties at the software giant. He's leaving in order to begin a second life as a full-time philanthropist and to explore his dizzying range of intellectual interests.