More and more rich people are choosing to give their money away before they die. Facebook founder Mark Zuckerberg has pledged to give away 99% of his family's Facebook stock - a gift estimated at the time to be worth $45 billion dollars. Some mega-donors are even pressing to spend donated funds their own lifetimes.

Joel Fleishman, a preeminent scholar on philanthropy, compares this current trend with the more traditional approach of perpetual foundations which are designed to last for generations. Fleishman's  book is Putting Wealth to Work - Philanthropy for Today or Investing for Tomorrow.