Noticed this morning that after adding History/Restore functionality to the AxKit Wiki that someone had put some pages back to what they were at the start of the history. Very strange. So I fixed some of the pages again, and checked the IP address:
Thu Dec 12 07:19:29 2002 - 22.214.171.124
So I did a lookup on that IP:
126.96.36.199.in-addr.arpa name = crawl7.googlebot.com.
It seems that I had stupidly made my "restore this version" code in my history pages just be a plain link. Despite having querystring params in it, google merrily clicks that link. Thus restoring the first version of every page on the site.
So I've now made the "restore" a form button. Hopefully it won't get clicked by bots.