NOTE: the following description refers to the current version. I'm currently porting it to Django at http://code.google.com/p/django-atompub/. This will, amongst other things, change persistence.
Demokritos is a Python library and content repository implementing the Atom Syndication Format (RFC4287) and Atom Publishing Protocol (draft-ietf-atompub-protocol-08).
Persistence is via a subversion repository. You'll need Subversion 1.3 with the SWIG Python bindings built.
Download alpha at http://jtauber.com/2006/demokritos/demokritos-0.3.7.tgz
Subversion at http://pyworks.org/svn/demokritos/
Mailing list at http://pyworks.org/mailman/listinfo/demokritos
Demokritos requires Python 2.4.
The source code is made available under a GPL license. Email me for alternative arrangements.