http://www.wikipedia.org/wiki/Foobar?md5=1234f53fa34f253f3453abf00f549120 which would identify a unique version with high probability, and also provide a way of verifying the integrity of the old version
Well heck, why use the name at all? (After all, pages can be renamed.) Add a hash field to the table, index it, and presto! Lookup an arbitrary version of any page, no matter how it's been shuffled around:
http://www.wikipedia.org/cite/1234f53fa34f253f3453abf00f549120
Yep, renaming is a sticky issue here, and the fact that "current" articles and old version are in different tables makes implementation a pain. As an initial effort, I think a title/date link could be implemented that will work most of the time and only fail on renamed articles; at some later point in the evolution of the software we can make it work correctly in all cases. I don't see any way the hashes wil help.