On GNU/Linux, Mac OS X or other Posix like OS, you can serve the standard port 80 used for web serving, but you must run as root for this.
Set port to 80, and verify that user and group exists on your system. If not, set them to an existing user, meant for web serving. If needed, chown your wiki dir to this user and group.
Run moin.py as root:
$ sudo moin.py Password: Serving on localhost:8000 Running as uid/gid 70/70
Test your wiki at http://localhost/