Further to point #4 on Rob's answer, I would further propose that there is a trust system in place for approving the edits, much like how a user can build up flag weight when flagging something for moderator attention.
So if I make the first vote, and the next person concurs, then that is a positive weighting for my edit approval authority . Once I have reached a certain level then it can require just my vote to approve the edit. This system is reasonably fool-proof, as the second approver has no way to see who the first approver was.
However I disagree with the proposed badge being bronze or silver - it should be gold (with a higher threshold to reach it), as that promotes longer term positive behaviour.
I mention this because I have been quite regular with my trawling of the pending edits list (and I've voiced my opinion about it more than once). It can be a tedious job to do properly, especially when people jump in making large volumes of low quality edits, or someone has a couple of hours to spare and decides to go to town on a wiki entry that needs careful scrutiny.
