A software system that implements the features of the OriginalWiki.
Python based Wiki clones:
ZWiki: http://joyful.com/zwiki/ZWiki (a Zope product; an evolved version is used on http://www.zope.org, which is also the place to learn more about Zope)
MoinMoin based wiki clones:
MoniWiki in PHP, RCS revision, compatible with a MoinMoin data, editlog etc. ( under development)
Sycamore (MoinMoin with SQL backend)
See also WikiWikiClones