Clay Shirky, an adjunct professor at NYU who studies social media, gave a stirring talk at Web 2.0 Expo last week on the Web 2.0 revolution -- how it's harnessing all the brainpower made available by the societal changes of the past 60 years. That time was, until recently, wasted watching mindless television, but now it's being put to work on Web 2.0 projects, some profound and some silly, but all significant.

Shirky posts a "lightly edited" transcript, "Gin, Television, and Social Surplus," in which he attempts to answer the question that all Web 2.0 evangelists get from time to time: "Where do people find the time?"

Did you ever see that episode of Gilligan's Island where they almost get off the island and then Gilligan messes up and then they don't? I saw that one. I saw that one a lot when I was growing up. And every half-hour that I watched that was a half an hour I wasn't posting at my blog or editing Wikipedia or contributing to a mailing list. Now I had an ironclad excuse for not doing those things, which is none of those things existed then. I was forced into the channel of media the way it was because it was the only option. Now it's not, and that's the big surprise. However lousy it is to sit in your basement and pretend to be an elf, I can tell you from personal experience it's worse to sit in your basement and try to figure if Ginger or Mary Ann is cuter.

And he quantifies the surplus. All of Wikipedia, "every page, every edit, every talk page, every line of code, in every language that Wikipedia exists in," required around 100 million hours of human thought to complete. By comparison, TV in the United States alone consumes 200 billion hours of people's time. Put that another way: If you consider the time spent to build Wikipedia as a single unit of human brainwork, then America spends 2,000 Wikipedia projects per year on TV.

Watch the video of the entire 15-minute talk:

I've been following http://nielsenhayden.com/makinglight/archives/010186.html#010186 discussion of Shirky's speech at the blog Making Light, and some of the people accuse Shirky of saying all television is stupid, and then they go on to defend contemporary television. I don't think that Shirky is saying that -- but even if he is, so what? That would make him wrong on that minor point, but, still, he's right on the larger issues: We in the West, and especially Americans, have wasted an awful lot of time watching television, and Web 2.0 gives us a way to harness that time to do useful work. And we've just scratched the surface of how we can spend that time productively, using the tools that Web 2.0 provides.

Even if the product of Web 2.0 isn't always useful -- even if it's just a bunch of folks jabbering away on Twitter, or creating LOLcats, or playing in Second Life or World of Warcraft -- then it's still participatory. It still involves exercising your brain for something other than watching Gilligan. It's creative play, it makes us smarter.

The value of creative play is emerging as a theme for me over the past couple of weeks. Earlier today I did a blog post about how Internet fans of the TV show Lost provide surprising examples for people looking to use Web 2.0 for business.