It has not slipped my attention that the most valuable companies in technology industry today tend to be culturally oriented (Goog, Apple, RIMM etc). Sometimes also called consumer oriented technology. Contrast this to the most valuable companies of the 90s which were infrastructure oriented. One could justify this trend to reasoning derived from study of economic business cycle which says first there is overinvestment in a trend followed by bust and painful restructuring and another (and longer) boom. Analogies are drawn between railroad construction bubble followed by bust followed by boom. Using this reasoning, the internet industry should have restructured and the next killer application should have been business oriented. Instead what we seeing is the killer application for the internet is "Cultural Networking".
I think the driver is shifting demographics in the world. Rutgers university did some research on the demographics in US, specifically, of people between 18-25 years of age. The research calls this group the "Millenials". SF Chronical earlier this year published a story on this group and their economic behavior. Interesting tidbit from the article is that this generation (approx 70M in strength) is just as large as the boomers (77M) generation. Lot of research has shown that rise of consumption driven economics in the US was due to boomer's purchasing habits. Today, it is these millenials who are driving the consumer economy, I think.
This explains the increasing adoption of electronics networks (on internet) to communicate, form opinion on product and purchase of the same.