I don’t yet have an iPod … but I’m close to getting one.  I do
want to take advantage of podcasts however … so when I saw this I
liked it.  I am looking for something exactly like this.  I
simple background process that would grab the podcasts that I’m
intersted in, manage my local cache, and build and update playlists for
me.  I’m going to experiment with this one:

Podcatcher 0.1.3. A podcast download tool. [freshmeat.net]