I don't know how many people have seen this, but it's rather interesting -- an essay by Clay Shirky titled "A Group Is Its Own Worst Enemy":

http://shirky.com/writings/group_enemy.html

Shirky mentions Wikipedia several times, calling it "the most interesting conversational artifact I know of, where product is a result of process." More interestingly, though, he examines the nature of human group dynamics and makes a number of observations that I think are worth bearing in mind when thinking about how to deal with problems like trolls and arbitration. Here are some relevant excerpts:

"The likelihood that any unmoderated group will eventually get into a flame-war about whether or not to have a moderator approaches one as time increases." As a group commits to its existence as a group, and begins to think that the group is good or important, the chance that they will begin to call for additional structure, in order to defend themselves from themselves, gets very, very high.

[SNIP]

 So the core group needs ways to defend itself -- both in getting started and because of the effects I talked about earlier -- the core group needs to defend itself so that it can stay on its sophisticated goals and away from its basic instincts.

[SNIP]
 All groups of any integrity have a constitution. The constitution is always partly formal and partly informal. At the very least, the formal part is what's substantiated in code -- "the software works this way."

 The informal part is the sense of "how we do it around here." And no matter how is substantiated in code or written in charter, whatever, there will always be an informal part as well. You can't separate the two.

[SNIP]

 Users have to be able to identify themselves and there has to be a penalty for switching handles. The penalty for switching doesn't have to be total. But if I change my handle on the system, I have to lose some kind of reputation or some kind of context.

[SNIP]

Second, you have to design a way for there to be members in good standing. Have to design some way in which good works get recognized. The minimal way is, posts appear with identity. You can do more sophisticated things like having formal karma or "member since."

[SNIP]

Three, you need barriers to participation. This is one of the things that killed Usenet. You have to have some cost to either join or participate, if not at the lowest level, then at higher levels. There needs to be some kind of segmentation of capabilities.

--Sheldon Rampton