Jessica Leber, on Technology Review:
Facebook has come a long way since it was first hosted in Mark Zuckerberg's dorm room and expanded as he rented additional servers for $80 a month. By late 2009, Facebook disclosed it was using about 30,000 servers, and since then, the number has more than doubled.
Can you imagine trying to patch sixty thousand machines? Leber reports that Facebook spent $1 per active monthly user to deliver the product. That's a dollar that the user does not pay to play. Except now they're a publically listed company with shareholders. And their share price is tanking.