There are some hacks to get RSS enclosures into Wordpress 1.2, but I just came across this on the Wordpress support forums: TextDrive Community Forum / Request for enclosure_type and enclosure_size fields
It's already baked into Wordpress 1.3-alpha-4, and so will be available in the next version. I'm not quite ready to start messing with alpha software (well, not someone else's alpha software...), but am looking forward to this... If I give podcasting a shot, I may just bite the bullet and upgrade to 1.3-alpha... Or, I may just try this mod for Wordpress 1.2.
UPDATE: I decided to install the hack mentioned above - didn't want to mess with alpha software, and didn't want to bork my customizations (and Kubrick) yet... This post now has an enclosure attached, and it should be visible in the RSS feed. Any podcasting experiments I do should automagically appear in that feed...
UPDATE: 2005/01/19 I just upgraded to Wordpress 1.5 (nightly build of the alpha) and support for enclosures is now included out of the box. If it doesn't pick up the .mp3 link and create enclosures automatically, just add a custom field to the post, as described here.