(As a warning to others, wikien-l@nupedia.com goes into a black hole. The old lists work at both @nupedia.com and @wikipedia.org. Jason, can you fix this?)
Ultimately, I would say that it is perfectly o.k. to ban people if, after a reasonable period of time, they appear to be unwilling or unable to work together with others in a collegial spirit of mutual respect.
Wikipedia is not Usenet. It is not the right place for people to attempt to put forward particular ideological positions. It is important for all ideological positions to be put forward in a fair manner, and it is therefore valid for people with a particular ideology to work on Wikipedia to ensure that their viewpoint is fairly represented. But the essential here is that people from all viewpoints should be working towards NPOV. To fail to do so is to fail to work together with others in a collegial spirit of mutual respect.
Wikipedia is not a joke book. User names like Throbbing Monster Cock are inappropriate. TMC's contributions have been perfectly o.k., as far as I know, but his name is clearly chosen in an attempt to be funny or (likely) to deliberately annoy people. TMC has argued that changing his name is tantamount to the use of force against him. This argument is stupid, because he has no property interest in his username, but if he wishes to press it, he should write to me personally about it, as this was my decision.
We should take great care to ensure a diversity of contributors. We should take great care that people are not banned for making policy proposals that are annoying to us. We should take great care that people are not banned too soon, even for breaking the rules.
For ip addresses, anonymous contributions, we should continue our policy of banning them for simple vandalism at the slightest provocation.
For usernames, we should be more forgiving, but only because the fact that someone has taken the effort to login suggests that there is some hope of sincerity. Even so, simple vandlism is ample grounds for a ban.
The more difficult cases are cases like Lir, or TMC. TMC has committed only one violation -- the selection of a deliberately annoying username. His contributions are, apparently and to date, not bad. Lir, on the other hand, has been uncollegial and rude to others on multiple occassions, and has received ample warning.
--Jimbo