True, but taking Facebook as an example, it's IPO'd with a 100:1 P/E ratio. It would take 100 years at current earnings in order to pay for its current value.

True, but taking Facebook as an example, it's IPO'd with a 100:1 P/E ratio. It would take 100 years at current earnings in order to pay for its current value. So, the question is: will they double revenue for enough consecutive years to bring that P/E ratio down? If they manage it, it will be a very impressive feat. (for the record, I'm not saying it's a bubble, and I'm not necessarily saying FB is overvalued. I admit that they have a lot of bright people and are probably the best-poised company right now to develop completely innovative revenue streams)