It looks like Bill Gates's trip to India worked: Billionaire Anil Agarwal was persuaded to join the Giving Pledge after meeting with him.
"Anil Agarwal, the billionaire founder of Vedanta Resources Plc, said he and his family decided to donate 75 percent of their wealth to charity after meeting Bill Gates, the world’s richest person. Agarwal has a fortune of $3.3 billion that includes an almost 70 percent stake in London-listed mining and energy group Vedanta, according to the Bloomberg Billionaires Index. Gates, the co-founder of Microsoft Corp., has a fortune valued at $84.7 billion." -- Bloomberg News