If Facebook's profits touch $1Billion this year (as is expected), the valuation of $100 billion puts it at a P/E of 100. Thats high, but not too high for a growth company (Amazon has a similar number). In fact, the forward looking P/E (assuming Facebook might make $2 billion next year) is a (relatively) low 50. Google has a P/E of about 15. One of the reasons that the P/E is so low is the belief that Google has grown a lot, and wont grow much more.

To be honest, this is somewhat of a disappointment. The companies that solve 'hard', core-tech problems like Google and Microsoft are falling behind. Sad. Sad.