Wikipedia's methods to deal with trolls are broken. I'll refer to 2 cases, one I'm not involved in, the other I am.
The former is Irismeister, who, as well as engaging in a prolonged edit war on [[Iridology]], has now threatened legal action against not one but two other users. Is this acceptable behaviour now? He remains unbanned.
The latter is User:Plautus_satire, who has engaged in edit wars on:
[[Quasar]], [[Laser star hypothesis]], [[Albert Einstein]], [[Black hole]], [[September 11, 2001 attacks]], [[Space Shuttle Columbia disaster]] and others.
A look at the full (ie 500 edit) history of [[Black hole]] shows that on that one page he's been reverted by me, SheikYerBooty, Cyp, Jwrosenzweig, Isomorphic, Modemac, Morwen, Curps, and an anonymous IP.
He has had similar wars on other pages. Even after 8 days, and certainly after having had NPOV pointed out to him, he continued the insertion of opinion as fact, for example, on [[Laser star hypothesis]], stating categorically that Hubble is a spy satelite.
According to a a poster at Apollo-moon-hoax groups, who commented at [[Wikipedia:Requests for comment/Plautus satire]], he has been banned from two such groups. Said poster gave a link:
http://www.clavius.org/plautus.zip
At the above is an archive of Plautus's messages to the Yahoo Apollo group, in which he sends literally hundreds of messages, often abusive, in the space of a single week. This suggests to me his motives are simply stirring up arguments, rather than any genuine desire to contribute.
[[User:Silsor/fanmail]] contains several extremely abuse emails from him when he was temporarily banned. As has been noted on this list, he also spammed just about every sysop in connection with that event.
Now, I freely admit I have not always acted well when faced with Plautus - I have occasionally adopted a sarcastic and condescending tone, for example. As a result of feeling I was in too deep, I decided to try to take a break from Wikipedia for a while. Yet even after this was pointed out to him, he repeatedly trolled my talk page with absurd complaints about me removing comments from it.
Lest anyone should think it's just me who has a problem with this guy, there is a vote at [[Wikipedia:Requests_for_comment/Plautus_satire]] where, at the time of writing, 14 people are in favour of him being banned, with 5 opposed.
Yet he remains unbanned.
Supposedly, instead of banning him, we now have to mediate with him. This is quite literally insane.