I think Kirsten Anderberg's suggestion of letting authors decide whether comments will or will not be allowed is interesting. However, if someone is prevented from adding comments to an article, she or he can still post a stand-alone article.

Putting the question of trolls aside for a moment, I think that comments make Indymedia special. Having articles with no comments is like reading an ordinary newspaper. The benefits of an interactive publishing community far outweigh the drawbacks. We can't let a handful of mean and unreasonable people ruin it for everyone. The punishment (taking comments away) may be too severe for the crime.

I think the best strategy for dealing with trolls (even better than hiding their posts) is to respond to the substantive comments they make (if any) and ignore the inappropriate parts. If we ignore the barbs and insults, trolls will learn quickly that no one is listening. Trolls seem to thrive on attention. Cutting off that attention will cause them to lose interest.