Bubble Bubble Sign Of Trouble

The thing about a bubble is that while people worry about it, no one is actually sure whether they are in one, and especially when it will be over. The other thing about bubbles is that they keep happening because they are the result of human nature (greed and self-deception):

"Less than a decade after the dot-com bust taught Wall Street and Silicon Valley investors that what goes up does not keep going up forever, a growing number of entrepreneurs and a few venture capitalists are beginning to wonder if investments in tech start-ups are headed toward another big bust."…

"The chief evidence, according to industry experts and analysts, is the way venture capitalists and established companies are clamoring to give money to young companies, including those with only a shred of an idea. They are piling into me-too start-ups that imitate popular Web companies that already received financing. Companies that involve social shopping, mobile photo sharing and new social networking are finding it easy to attract investors because no one wants to miss the next big thing." (from Sillicon Valey Shows Sign of a New Dot-Com frenzy)