IMHO, facebook is GREATLY overvalued, but only time will tell if it's true. Their investment in price assumes that they will continue to grow and will still have no competition in a 1/2 decade.
$120 billion, or $80 billion - depending on who you talk to. Google is making cars that the blind can drive and glasses we saw in terminator. Facebook, they're giving us timeline. GE makes light bulbs, owns NBC, create military jets. Facebook gives us status updates. You think facebook can possibly be worth 1/3 of ALL of GE?
Of course, I'm joking a lil about facebook's offerings. I know they offer far more. However, to think they're going to be the only dog in town doing what they do is just being ignorant.
Tech is filled with creative people who fuck shit up all the time. Just as facebook made some people turn heads at MSFT and GOOG, so will someone else in the future.