Here, then, is what I'll propose as the Law of the Wiki: Output quality declines as the number of contributors increases. Making matters worse, the best contributors will tend to become more and more alienated as they watch their work get mucked up by the knuckleheads, and they'll eventually stop contributing altogether, leading to a further fall in quality.
What you can do in order to save projects like the wikipedia from turning into moronic proclamations? One option, as Carr suggested, is to impose some form of centralized control. This is also what is done with open source projects, wherein a lot of effort is made to ensure that the crap is weeded out. I feel that this form of control is more cumbersome to implement. It is not about the debate if a few people are more equal than the rest, but the loss of expertise which is utilized in checking and approving what others have done is sometimes too overwhelming, especially if everyone contributing considers himself to be an expert. At the same time, it is against the basic tenet of "horses for courses". You should not, in an ideal world, use your best people to do work that can be done by others, and fritter away their energies which could have been spent better doing more worthwhile things.
Another option is to form a select band, or a "club" of contributors. Entry is by invitation/reference only, and thus quality is more or less under control. This makes me wonder about the viability of such an option for a project like wikipedia. Can you have a few people who know the best about all the things for a project like an encyclopedia? Probably not. However, if you talk of a project like Linux, the answer can be a resounding yes. The fact of the matter is that the most important contributors to projects like Linux are people who are few in number, and they are the ones who really contribute the most. One needs to have this "core", and really leverage their skills. Of course its nice to be open and let others contribute, but ultimately, its the "core" that matters. This was something similar to what I commented in my post when I said that just being open source doesnt mean anything.