He's only 26 but every new card that he turns over seems to add to Mark Zuckerberg's incredible wealth. How lon before he's No 1?

In Forbes magazine's list of the World’s Richest People in February, Facebook was valued at a "mere" $50 billion, putting Zuckerberg’s net worth at around $13.5 billion.

Now, based on the 40 percent valuation increase, Forbes estimates that his mostly paper fortune is upwards of $18 billion. Facebook’s other billionaires—Eduardo Saverin, Sean Parker, Dustin Moskovitz, Peter Thiel, and Yuri Milner—are much richer, too.  Last autumn, Zuckerberg’s net worth passed Apple’s Steve Jobs. Based on this new $18 billion estimate, he’s also now richer than Microsoft head Steve Ballmer and Google co-founders Sergey Brin and Larry Page. Still ahead: Bill Gates of Microsoft and Oracle’s Larry Ellison on a respective $56 billion and $39.5 billion. How long before Mark passes them too?