Here is a list of known Python-based WikiEngines
Hatta -- a Wiki which runs out of a Mercurial repository whose pages are just the files in that repository
Markdoc -- a lightweight Markdown-based Wiki system, public domain
MoinMoin -- an evolution over PikiPiki that you're using now - multiple ways to run, plugin-based architecture with lots of plugins and large community, GPL
MonkeyWiki -- another PikiPiki fork that claims to be simple to install/use, single file, very flexible templating, rewrite-friendly
http://homepages.kcbbs.gen.nz/tonyg/projects/pyle.html -- GPL wiki with multiple VCS backends, email notifications, edit by FTP and lot of other features
sahriswiki -- Mercurial backend support, plugins, MIT licensed.
Sphene Community Tools -- Django based wiki and forum applications.
Sycamore -- seems to have roots in MoinMoin, but looks a little slicker while not as full featured. Uses a Postgesql or MySQL backend. GPL
Trac -- an enhanced wiki, issue tracking and source code browser system. Supports multiple markup formats including MoinMoin, ReStructuredText, html, and textile. Runs as FastCGI, WSGI or standalone. Pluggable architecture with focus on simplicity.
WyPy -- a ShortestWikiContest contender, 23-, 18-, and 11-line versions.
zim-wiki at http://www.zim-wiki.org -- WYSIWIG personal/desktop wiki with index, links, image inclusion, checkboxes and bulleted lists, equations, graphviz; calendar, ToDo; prints to clean html. Customizable, all-python over gtk2, inbuilt-server, uses filesystem as db; debian packaged. Documentation. Actively developed 2012.
Archaeology (dead, missing and outdated)
CyberPublishing -- a wiki-based web publishing framework written in Python; GPL
Luminotes -- a WYSIWYG personal wiki notebook for organizing your notes and ideas. Not currently developed.
Not-Yet-Named Wiki -- runs on Webware. Supports static publishing, WYSIWYG editing, ReStructuredText
http://moinmo.in/PikiePikie -- Python-based, lets you put a WebLog on any page (based on PikiPiki)
PikiPiki -- Python-based, completely standalone, GPL, famous ancestor of most Python wikies