“… portrays a company that makes the vast majority of its money from selling display ads targeted to its users who have revealed to Facebook much about their lives…”
Full article (together with some interesting earnings) over at
http://www.washingtonpost.com/business/economy/facebook-ipo-a-look-at-what-we-learned-from-the-filings/2012/02/02/gIQAC3LElQ_story.html
Give away your personal details and your entire life to Facebook, they sell it and get rich… simples!