http://www.gladwell.com/2005/2005_09_05_a_bakeoff.html
Gladwell's thesis is that although open source projects, which we can probably loosely define to include ourselves, bring together great expertise, but also create significant friction between the members of what we call "the community". If I could graph Gladwell's thesis and borrow some economic jargon, I'd say that there is some point on the curve where the marginal value of the cumulative benefits and disadvantages of expertise and friction is equal to zero. (Okay, I was trying to phrase this in a more simple way, but clearly I failed.)
The question is: have we on Wikipedia reached a point where our community is too big that the negative friction overwhelms the positive value of our expertise?
I'm just throwing this out for discussion, but I think this hypothesis may prove to be true in some areas - namely those frequently discussed on this list. But in less high-activity areas, such as quiet (i.e. not [[George W. Bush]]) articles, then we have a sufficiently small group of editors who have space to think and bring their individual ability to bear.
Johnleemk