Hi.
I just want to add one point to this debate. Wikipedia has escaped massive and targeted vandalism because it has avoided making any real enemies. In my opinion (and experience) _manually_ imposing policy on a self-policed community will result in bitter souls abusing the inherent _systematic_ freedom (that is, that anyone can edit any article).
But haven't we already dealt with such people?
* We've only had to deal with very few of them, so we haven't hit anyone with the skills necessary to damage Wikipedia.
* We've let the ones we've dealt with have their say for a long time first, probably making them spend their frustration, and become mostly bored.
* The IP banning is more a signal than an actual enforcement, and we've been lucky that these people seem to have accepted that signal.
Believe me, IP bans will only last so long. The "wiki miracle" could easily collapse - just looke at some of the IRC networks.
I can't make up my mind either way in the discussion in general here, but I think this is an important point that should not be missed.
-- Daniel