Billionaire Facebook co-founder Mark Zuckerberg (and our first millennial CEO), Carl Icahn, and 15 others have joined the Giving Pledge, a philanthropic initiative started by Bill and Melinda Gates and Warren Buffet.

According to the New York Times Dealbook blog, the Giving Pledge has been criticized as a publicity stunt. This criticism was also leveled at Zuckerberg when he donated $100 million to Newark schools in September. If it is a publicity stunt, it’s a pretty good one.

The campaign asks that billionaires pledge the majority of their wealth to charitable causes either before or after their death. According to the initiative’s website, the idea is to spur both philanthropy and conversation addressing the world’s problems. Others who have joined include hotelier Barron Hilton, investor Ronald Perelman, broadcast media mogul Ted Turner, and New York Mayor Michael Bloomberg.

Other new additions include financier Michael Milken and his wife Lori and Morningstar founder Joe Mansueto and his wife Rika.