I like listening to podcasts on my Zen Vision:M player. The Zen comes with a decent enough podcast tool called Zencast. Zencast has an option to convert audio podcasts to video format. They take the description of the podcast and display it as text in the podcast. This makes it handy to see what is on a podcast by playing it for a few seconds. The other advantage is that it categorizes them separately from the music, making it easier to drill down and locate the file to play.
Sometime in December, NPR made a change to their servers and is preventing the Zencast application from downloading any podcasts from NPR. You get the message: "Unable to download due to a connection error." It happened sometime between 12/3/07 and 12/04/07. Other podcast sources work just fine, the problem is limited to NPR.org. I can directly download NPR podcasts through a browser, but I lose the extra functionality provided by the Zencast application. I'm not the only one getting this problem, I saw references to it here, here, here, and here. The best guess is that the NPR server some setting that tells clients what functionality that they support and it's breaking the applications that actually check those settings.