David Gerard: there isn't a central bibliographical reference base, as some have mooted. If you can code something that will both work and be sensibly usable by casual editors, I suspect it would be most welcomed ...
Take a look at the Wikicat/Wikicite idea on meta: http://meta.wikimedia.org/wiki/Wikicite http://meta.wikimedia.org/wiki/Wikicat
I was told recently that most of the Wikicite code has been written.
For the longer term.....at Wikimania we discussed a detailed fact-checking process, possibly using Wikicite, and this would use a separate list of sources, so a user who wants to check a fact in a validated article could find the source for every fact...but that's at least 2 years away, I'd say. I understand that Wikicite/Wikicat would support such a feature. See the link below for more detail: http://en.wikipedia.org/wiki/Wikipedia:Pushing_to_validation
Martin A. Walker (User:Walkerma)