Mailman
A useful paper from the University of Washington (home of the PubCookie authentication system) describes how they integrated PubCookie's 'container based' authentication with Mailman (http://www.gnu.org/software/mailman/). PubCookie and Raven are almost identical in their operation and requirements, so a similar approach could probably be used with Raven and the mod_ucam_webauth module. In fact, mod_ucam_webauth has an extra feature that might make this even easier - the AAAlwaysDecode directive will cause the module to decode its cookie for requests even if authentication isn't required, though of course something has to set it in the first place. Using this you might be able to skip the "stub" application and its SHA1 encrypted cookie that Washington used.