Chris at bitforbit wrote a perl script to recurse through directories and generate a podcast for each directory. You can pick it up here.
He also noted:
Oh, one thing worth mentioning that may not be obvious right off the bat is that the File::DirWalk module is required, so if you do put it up on your site, you may want to mention that.
He was nice enough to provide a copy of it to me as well. You can download it here. I'd click the link above, though, as he may have updated it in the meantime.