I was recently sent a link to this article - Tapping the Wisdom of Crowds: An Integrated Model - it's certainly worth a read if you have 10 minutes.

A lot of it makes perfect sense; getting a collective answer on a complex problem (although, as the author states, the problem should be broken down into its basic elements, otherwise people will get the wrong end of the stick due to outside influences, miss information etc) proves to be more reliable (read realistic outcome?).

I wonder if there are any fully documented case studies on this - after it, when you think about it, this sort of thing goes on all the time, we just don't notice it!