The Problems Wikis have with Search Engines...

Rollback mystery solved: The search engines did it! 6. June, 2004
Apparently random rollbacks have been occurring for some time now, but with the IP logging in place, it was easy to assign the blame. Search engines have traversed the site and have been “clicking” all the rollback links. So now the rollback link is done in javascript to keep those pesky engines at bay. This fix will be part of 0.9.2 and is already in effect on instiki dot org.

http://instiki.org/show/HomePage
and
http://instiki.org/show/SearchEngines