Wikipedia
MoinMoin
MoinMoin is a wiki engine implemented in Python, initially based on the PikiPiki wiki engine. Its name is a play on the North German greeting Moin, repeated as in WikiWiki. The MoinMoin code is licensed under the GNU General Public License v2, or (at the user's option) any later version (except some 3rd party modules that are licensed under other Free Software licenses compatible with the GPL).
Dozens of organizations use MoinMoin to run public wikis, including free software projects Ubuntu, Apache, Debian, FreeBSD.