This might be something of a, “Duh, Fred!” statement. But, there is now judicial authority (in America at least) to say that Wikipedia entries may not be used as evidence.
The decision (also available here, in case the first link dies) is an unpublished appellate opinion of the New Jersey Superior Court Appellate Division. That Court explicitly says those opinions don’t bind any court and can’t be cited in court. It’s probably an understatement to say it’s use in the USA is limited, and even more so here! (I mentioned a basic introduction to USA jurisprudence in researching united states law.)
I read about this in the MILO forums run by US attorney Ben Stevens. It’s mentioned elsewhere in the blogosphere, and I think most picked it up from the New Jersey Law Journal.
Slaw blog explained the reasoning simply: it’s potentially easy for a party to edit entries for its own advantage, and hard to verify or challenge the accuracy of the article.