Business Week in the recent article put it dead on calling Web 2.0 companies as a season TV show:

Digg’s collapse has become a cautionary tale for so-called Web 2.0 companies in Silicon Valley, even the current crop of superstars, like Facebook and Twitter. The basic problem is that these new-media companies don’t really have customers; they have audiences. Starting a company like Digg is less like building a traditional tech company (think Apple or HP) and more like launching a TV show. And perhaps, like TV shows, these companies are ephemeral in nature. People flock in for a while, then get bored and move on.