Last Monday someone shared on Twitter a link to Seth Godin's post "If Craigslist cost $1". I don't read his blog, but this idea got me interested. I shared it at work with Noah, and his take was that Metafilter already applies this model, by charging its members $5 for service - and thus creating "one of the most active and highest quality community websites out there." (Noah's quote).
So, right, prohibitive pricing is a proven and efficient mechanism to coordinate demand.
In digital, things may turn out to be a little bit more complex. Prohibitive pricing indeed may work perfectly well for communities like Metacritic, where what is charged is a membership. Craigslist, on the other hand, is a service - and not a community. When we pay for a service, we expect not only access to it, but also to get something in return (at least, it seems to me that things work out that way). I expect Netflix to let me stream movies I want; I expect ZipCar to be where designated; I expect Time Warner cable to work and its technicians to show up on time (often an unreasonable expectation). So, while it is correct that charging $1 will create a "tightly organized community", it may also make people change the way they use - and benefits they expect from - Craigslist as a service.
(Somewhat related: while I think that micropayments actually can make a lot of sense on the web, I don't think there's should be regarded as a blanket approach - precisely because people's habits, expectations, and motivation considerably differ from one thing to another. For example, a piece of content is not just that: while people easily pay .99 for a song, I am not sure they would be willing to pay the same amount of money for a newspaper article.)