Depends if Facebook is the main way to socialize for the next century. Imagine having that much data on that many people and owning that channel! That's worth a lot of money.
Yes, considering the previous Facebook didn't nearly last as long. I'm thinking that social networks don't have nearly as high of a shelf life than you think.
When it comes to investing though you invest in a management team and not a product. The rate of change is increasing, all the products on the market today will be well and truly obsolete in a few years, even the market opportunities themselves could change
It's things like Facebook putting 'the hacker way' into their DNA and being able to retain top talent that makes the company worth anything. If you took the facebook source code and all their customers away they'd probably have a pretty good chance of making something else that's quite good. Today anyway, but if tomorrow they can't it'll be because they somehow lost their way and let the MBA's in. Kodak had a great place in the market but they just couldn't successfully adapt
I haven't looked at the price but if I was in the USA I'd probably buy some shares, the google float of $100 seemed outrageous at the time, and unless they get further involved with Microsoft I'm pretty bullish that they'll keep going up
In my mind, that's the big gamble with Facebook. It could either be THE source for socializing for 100 years (and hence very valuable), or it could be another MySpace (etc.), and hence not worth a lot.
The cynic in me, would say that people who own stock now don't think it would last and are getting out when it's at it's top.
Not even the entire Bell system would be worth $1 trillion today, and unlike Facebook, people actually had to use the Bell system, it wasn't just a source of idle entertainment.