Why facebook?

Now this stock is going up. I have been "explaining" facebook bad performance, with Eduardo's Curse.

For the people who took me seriously, I come clean, I was joking, nobody knows the reason why the beginning of facebook path in the stock market is as it is.

I wonder here, why facebook is worth over one hundred billion dollars, and digg is not a public company?

Digg is concentrated in the technical aspect of the Internet, like slashdot.org; facebook is for everybody, even our grandmothers.

Given the huge costumer base, it is not clear to me where facebook is going: Up, down, whatever!?