At 26, Facebook founder Mark Zuckerberg has become the youngest member of a gang of billionaires who have pledged to give away half their wealth to charity. Zuckerberg is one of 16 new tycoons, including AOL founder Steve Case, to sign the list, pushing the total number of signatories past 50. The pledge was started by Bill and Melinda Gates last year, and includes high-profile billionaires like Warren Buffett and New York mayor Michael Bloomberg. Zuckerberg, who is worth an estimated $6.9 billion, said, “"There's so much that needs to be done, it would be better to start now."
