Google: $187B market cap.
Amazon: $55B market cap.
Yahoo: $22.5B market cap.
Facebook: $14B market cap in SecondMarket
Twitter: ~$1B post-money.
Looking at these graphs, I can't help but think that DST's $10b valuation was a steal. I know I would be a buyer, even at the alleged SecondMarket value (if only I was an accredited investor).
The question of course is how well Facebook will be able to monetize. Google invented one of the simplest and most effective moneymakers out there. They have one revenue stream with ridiculous operating margins that generates the vast majority of its revenues. As far as I know, Facebook doesn't have one truly dominant revenue stream yet. That said, I believe Facebook is becoming a more entrenched part of our online lives than Google. As Facebook Connect log-ins become increasingly ubiquitous, will Facebook displace Google as the most valuable internet property?