So here is how this works. Zuckerdick picked out a brokerage firm, who sells "preferred stocks" in Facebook to really rich people. They get these pretty cheap. Then they form a company "Board" who decide how many shares of stock they will sell in the IPO (initial public offering). These will start out at the same price as the "preferred stock" all those rich people have.
The rest of the world will want to get in on the ground floor, and drive up the "value" of all of the stock by buying at higher prices. Once things peak and Facebook gets pressured to put up more ADs, so shareholders can get higher dividends, they will bail and sell the stock.
Facebook will suck more than it does today (which is hard to believe). A lot of rich people will be even richer. Any 401K that invested in Facebook will take a hit when people flock to the next "big thing". We saw this before, it was called the .COM bust in the 1980s. Delete your Facebook profile on December 7th and screw the IPO. Screw the rich who are banking on it, like they have been screwing the rest of us for decades.