It's certainly beginning to look like a Bubble. A few things - 1) Everyone is assuming that revenue will explode, and more importantly, profits will really, r

It's certainly beginning to look like a Bubble. A few things - 1) Everyone is assuming that revenue will explode, and more importantly, profits will really, really explode. 2) Everyone is discounting intent. A social network for networking is very different from a site you go to to find jobs. The assumption that LinkedIn is going to destroy sites dedicated to job hunting is just that - an assumption. There is a higher chance that people will not change their intent from social networking to jobs - than there is that people will. 3) Everyone is discounting competitors. NEW The biggest warning flag to me is the assumption that all these tech companies are just waiting to hit some magical figure (say 250 million users) and then they will turn on the magic tap of unlimited profits. A company that makes a lot of profit from the get go is very different from a company that stumbles into a huge source of profit and those are both very different from a company that optimizes for customers of bad intent and thus never reaches high profitability. * NEW LinkedIn is worth $9 billion because Wall Street needs a way to get everyone's savings into their bonuses. The party will last for a couple of years. LinkedIn, Yelp, Groupon, Facebook, Zynga, etc. and every day people will be milked. The same strategy - release a small amount of shares and drive up prices - appeal to people's greed to make a quick buck. Then 90% of these companies will go down from 10 billion and $50 billion valuations to $1 billion and $5 billion valuations.