This is a seminal piece from Doc Searls, in 2004. It has bold and illustrative conclusions, such as this.

Except as the literal reciprocal of "producer," "consumer" no longer holds much useful meaning, except where the supply side of advertising talks amongst itself.

Internet as a market. What matters is attention.

In real markets (where everybody is a peer), companies can converse and relate directly to customers. Here you still have the scarce resource we call attention; but you also have a much better chance of earning it, by relating directly to the customer in ways that actually make your product, and your company, interesting and attractive.

And marketing must evolve to something consequently different.

Advertising, or whatever it evolves to
become (say, something people actually want to see and hear, rather than to avoid) therefore will play a much different role in this world.

Thanks to Tara for the reference.