At the moment you can change the metadata tags (eg, remove artist and have "speaker" instead), but the search and browsing criteria doesn't update to match it.

It would also be cool to be able to link metadata terms for the sake of podcasting. eg, I use "Speaker" instead or "Artist", but for the rss feed, it's expecting an "Artist" field. So I link the Speaker to Artist, and then the rss feed display the Speaker value in the Artist field.

This would allow custom metadata, but would still podcast properly (and browse properly!)