Microsoft Chairman and the cochair of the Bill and Melinda Gates Foundation was a guest on The Daily Show with Jon Stewart this week, almost three years since his previous appearance on the show. However, in just three years, Gates focus has changed dramatically. Whereas at the start of 2007 the Microsoft cofounder was busy advertising the young Windows Vista operating system, this time around he focused on his philanthropic efforts. Gates left Microsoft for a fulltime role with the Bill and Melinda Gates Foundation, choosing to attempt to provide solutions for critical global problems including health, poverty and education.