The central insight of Coase’s Penguin was that peer production is form of economic organization on par with the market (first explained by Adam Smith) and the firm (first explained by Ronald Coase). Benkler expands on this tripartite classification of organizational structures in The Wealth of Networks. He spends quite a lot of time pointing out that non-market, non-firm methods of social organization account for a substantial fraction of our economic lives. We carpool, have dinner parties, give directions to strangers, help each other move, etc. These activities generate goods and services (meals, rides to work, information) that could also have been obtained via the market, but for a variety of reasons we sometimes find that non-market organizational methods meet our needs better.
I think this is a point that libertarians tend to under-appreciate. In college, I dated a left-of-center girl who liked to shop at the local grocery co-op rather than a commercial grocery store. It was a topic of frequent argument. I’d point out the relative efficiencies of commercial grocery store organization, she’d stress fuzzier, more community-focused advantages: the sense of community, the superior treatment of workers, the closer connection between customers, employees, and management, etc.