As a side-effect of generating XSPF, it should be very trivial to embed the XSPF Web Music Player into a page on your site. (The player is open-source, and has a BSD License which allows it’s use even for commercial purposes.)
So if you’ve got a podcast, use WordPress 1.5.x, want a player on your site, and can drop a few files into place, let me know.
(Oh! If you are a WordPress Hacker and want to help me with this, please contact me, as my code is not up to WP-standards and I’d like to have some input on it. Thanks!)