I have seen hundreds of posts on Slashdot about incompetence and abuse of power by Wikipedia editors. NONE of these posts contained reference to the events described. Citation needed, indeed.

It is quite possible that the distribution is lognormal. I don't have a citation right now, but I know that some of these guessing distributions are indeed lognormal. That would mean that the geometric average is the correct formula, and not the mean or median.

Goldwasser,Kalai,Rothblum - Delegating Computation: Interactive Proofs for Muggles

http://www.mit.edu/~rothblum/papers/del.pdf

This is a theoretic, not immediately applicable result, but it shows that it is possible to set up such a distributed system so that it is immune to poisoning attempts.

You are the clueless one here. See some of the other replies to your post, most of them do have a clue. It is a shame that currently you are modded to the top, and they were not even moderated. New Scientist is prone to sensationalism, and this field is often misrepresented in the press. So I was actually quite surprised to see an informative and accurate piece such as this.