No it's not a bubble. Sure some companies are trading at absurd valuations: Facebook, Groupon but there is not this froth of worthless companies like there was in the .com boom. Airmailing dog food across the the country, indeed. One difference is that it is much more difficult to do an IPO these days (for better or worse). Another is that entrepreneurial experiments these days cost far less than 10 years ago, YC now, vs VC's then. The bubble this time around was financial with another due in 10-15 years.