As you may know, I do a weekly podcast with Jay Rosen called Rebooting The News.  

This is a heads-up to people who subscribe to the podcast. There is a problem with the feed that will cause some subscribers to not get every episode. (It could be a majority of subscribers not getting any episodes, depending on how their clients are programmed.) 

Technical: The problem appears to be caching. After a post is published, it builds the page, and caches the HTML. Somehow this is done before it realizes there is an MP3 attached. Eventually the cached feed expires, it rebuilds the feed, and now the MP3 is linked in as an enclosure. How long before this happens and how many clients have read the post and stored the guid and assume there is no MP3? Unknown. But a correctly written client that scans frequently will miss the MP3. My client does, for example 

Until this problem is fixed, you should manually visit the site periodically to see if there's a new MP3 available and download it to to your listening device.  

This is a repeat of a problem that hit our podcast in the beginning of the year. It was fixed, the feed was working properly for a few months, but it's broken again. The Automattic people are aware of the problem, and hopefully will have a fix soon. As I understand it, all podcast feeds on wordpress.com are broken, btw -- so if you're hosting a podcast there, you should be aware of the problem. 

We continue to use WordPress because Jay is very comfortable with it. We checked out Tumblr, and it's not any better at podcast support than WordPress is.  

A personal note, none of these programs work as well as the tools we had when podcasting was booting up in 2001-2004. Had our tools been this bad, there would be no podcasting, I'm sure of it. As these services have scaled, important features are breaking. This of course totally sucks.