I don’t recall this feature in iTunes 9. iTunes 10 apparently recognizes which subscribed podcasts I haven’t listened to in a certain period of time and automatically stops the subscription. On the side of the podcast title it will mark them with an exclamation mark inside a gray circle just like songs or videos that are missing from the library.

That last point is an issue in itself. Missing items in iTunes have always been marked with that icon. By marking neglected podcasts with the same icon, it can lead people to think their podcasts are missing. Of course, clicking on the icon brings up the dialog box above which explains the situation, but it’s still grounds for confusion.

It’s almost like how Apple uses the same tunes for the default SMS tone in iPhones as when Mac OS X finishes a disc burn or completes an installation.