Edge has a a very interesting and important talk by Clay Shirky (transcript and video here) on our "cognitive surplus". Worth reading all of it, but here a couple of key excerpts:
If I had to pick the critical technology for the 20th century, the bit of social lubricant without which the wheels would've come off the whole enterprise, I'd say it was the sitcom. Starting with the Second World War a whole series of things happened — rising GDP per capita, rising educational attainment, rising life expectancy and, critically, a rising number of people who were working five-day work weeks. For the first time, society forced onto an enormous number of its citizens the requirement to manage something they had never had to manage before — free time.
And what did we do with that free time? Well, mostly we spent it watching TV.
We did that for decades. ... Desperate Housewives essentially functioned as a kind of cognitive heat sink, dissipating thinking that might otherwise have built up and caused society to overheat.
And it's only now, as we're waking up from that collective bender, that we're starting to see the cognitive surplus as an asset rather than as a crisis. ...
So how big is that surplus? If you take Wikipedia as a kind of unit, all of Wikipedia, the whole project—every page, every edit, every line of code, in every language Wikipedia exists in—that represents something like the cumulation of 98 million hours of human thought. I worked this out with Martin Wattenberg at IBM; it's a back-of-the-envelope calculation, but it's the right order of magnitude, about 98 million hours of thought.
And television watching? Two hundred billion hours, in the U.S. alone, every year. Put another way, now that we have a unit, that's 2,000 Wikipedia projects a year spent watching television. Or put still another way, in the U.S., we spend 98 million hours every weekend, just watching the ads. This is a pretty big surplus. People asking, "Where do they find the time?" when they're looking at things like Wikipedia don't understand how tiny that entire project is, as a carve-out of the cognitive surplus that's finally being dragged into what Tim O'Reilly calls an architecture of participation.