Mark Zuckerberg, the $5 billion man

One thing has been overlooked in today's Facebook valuation announcement — how much the major players can now claim to be worth. A source tells us that Facebook founder Mark Zuckerberg owns about 30 percent of the company, meaning that the 23-year-old Harvard dropout is now a paper billionaire, four times over. That's more than Yahoo cofounders Jerry Yang and David Filo, and closing in on Google CEO Eric Schmidt. He is, possibly, now the wealthiest 20something in the world. (I checked on the Forbes Young Billionaire list, and the only one who was close was Albert von Eurosomething.) Other winners?

We've heard that Facebook not-quite-a-founder Sean Parker holds 5 percent of the company, now theoretically worth $750 million. That more than makes up for the payday he missed out on for Napster. And Peter Thiel, the PayPal founder who presciently backed Facebook? Sources put his stake at between 5 and 7 percent, or between $750 million and $1.05 billion. If he's ever able to cash out his initial $500,000 investment, it will prove one of the smartest moves in the history of the Valley. And if the Microsoft deal proves to be the last time Facebook is valued as high as $15 billion? Perhaps the most painful paper loss since the bubble burst.