The difference between Web 1.0 and Web 2.0

Came across the following quote by Joseph Lassiter of HBS on rkgblog:

The biggest single difference between Web 1.0 and Web 2.0 is that today you tend to get one 46-year-old CEO in Web 2.0 companies, whereas in Web 1.0 companies you got two 23-year-old-co-CEOs… People are older, wiser, and to some extent, more jaded.