Aw: podcasts/audio blogs?
It might well be, that the necessary RSS XML code is not (yet) supported by TikiWiki to have a full-fledged integration.
I'd go for Podcast Maker instead on the Mac, which is a great drag&drop tool which let's you easily create everything you ever wanted for Video or Audio-Podcasting. It will automatically upload your data to any kind of server and produce the necessary xml files.
All that's left to do for tikiwiki is create a wiki-page which has a reference to your podcast.xml file. I don't really see a big value in integrating audio/video support in a CMS like system anyway.
BR - Bernhard