THE RUMOR IS that sometime this year the young Mr. Mark Zuckerberg will be richer than…well, not Bill Gates, but richer than the late Steve Jobs. It will be the result of the first public offering of stock for Facebook–the business, web site, and cultural phenomenon created by Zuckerberg. Investors talk about it in terms of Visa and GM’s IPO–only more so. Facebook watchers are saying the IPO will net Facebook $10 billion and give Facebook a total value of $100 billion, 24 percent of which belongs to Zuckerberg. It would put him, at age 27 in May, ahead of Steve Jobs’ net worth and the 35th richest American, according to Forbes.