Facebook made a lot of people millionaires but it made 10 people billionaires.
The stock opened today at $38 per share.
Using that price, Bloomberg calculated the net worth of Facebook's richest employees and investors. They're now worth ten or eleven figures.
Chris Hughes, cofounder of Facebook, is now worth $935 million

Who he is: Cofounder of Facebook, college classmate of Mark Zuckerberg's.
Value of Facebook stake at $38/share: $835 million
Net worth: $935 million
Sheryl Sandberg is Facebook's COO. She's now worth $1 billion.

Who she is: Facebook's COO, former Googler.
Value of Facebook stake at $38/share: $1 billion
Net worth: $1 billion
Yuri Milner is now worth $1.1 billion

Who he is: Milner is the founder of DST, which made a big investment in Facebook. He owns ~ 12.5% of DST's Facebook shares.
Value of Facebook stake at $38/share: $400 million
Net worth: $1.1 billion
See the rest of the story at Business Insider