Will Zuckerberg and Chan's $45bn pledge change philanthropy?

Today's tech billionaires blur the line between philanthropist and entrepreneur. Time will tell if Facebook's CEO and his wife will succeed in doing good - but by then they might have changed the act of giving forever

It seems fitting that on the day that the Smithsonian's National Museum of American History unveiled its Giving in America exhibit - with Bill Gates and Warren Buffett presiding - Mark Zuckerberg, the CEO of Facebook, and his wife Priscilla Chan, made a claim for the inauguration of a new chapter in the history of philanthropy, one dominated by the mushrooming fortunes of Silicon Valley.

In a post on Facebook to their newborn daughter Max, the couple announced that they would turn over 99% of their Facebook shares - with a current value of around $45bnn - "during our lives" to advance a mission of "advancing human potential and promoting equality for all children in the next generation". This is a big deal, one of the largest philanthropic pledges ever made. But how much of a rupture it represents in the tradition of modern US philanthropy isn't entirely clear. The Smithsonian might not need to add another display case just yet.