Almost two years to the day since Mark Zuckerberg promised to give half of his wealth away to charitable causes, the Facebook  founder has announced (on his Facebook page, natch ) a donation that amounts to around half a billion dollars. The recipient is a Silicon Valley-based charity, the Silicon Valley Community Foundation, which will receive 18 million shares in his social network, which floated earlier this year. Its value? A shade under $500 million .
Two years ago he kickstarted his philanthropy and gave $100 million  to schools in Newark. Zuckerberg is a signatory of the Giving Pledge , which counts luminaries such as George Lucas , Michael Bloomberg  and, of course, Bill Gates  and Warren Buffett .