Has been removed from the iTunes Store?

This Apple Tech Note explains how the links relate to the Store:

http://www.apple.com/itunes/podcasts/specs.html#rss

scroll down a bit and you will see an illustration: unfortunately this is still the old design.

This indicates that the 'itunes:subtitle' tag in the top section doesn't get displayed, but within each 'item' this tag should populate the 'Description' column. I can't check on iTunes at the moment but from what you say they may have 'improved' things. Would you like to post the URLs of your feed and the Store page so I can have a closer look tomorrow?

I have now carried out a test with a dummy feed an can tell you exactly what happens when you subscribe (I can't say what happens on the Store page as that would involve submitting it, which obviously isn't practicable).

On subscribing, the top line shows the title of the podcast. The description column shows the 'itunes:summary' tag in the top section (not within an item). When you click on the 'i' button (without expanding the display to show the episodes) the pane shows the same 'itunes:summary' tag contents followed by the 'itunes:summary' for the top episode.

When you expand the display to show the episodes,and click the 'i' button on the top line you get only the 'itunes:summary' tag in the top section.

For each episode listing, the 'Description' column shows the 'itunes:subtitle' tag for the episode; when you click on the 'i' button for an episode you get the 'itunes:summary' tag for the episode.

I don't know whether this is a change from the previous arrangement, but the 'itunes:subtitle' tag works for the episodes.

This doesn't accord with your observations, but I did work through this carefully. I suggest you could experiment by making a duplicate of one of your feed, changing all these tags so that the content is the name of the tag, uploading the test feed to your server and subscribing manually in iTunes from the 'Advanced' menu (none of this will affect your real podcasts) so you can see exactly what is happening.

Your podcast is behaving exactly as I described when subscribing: the subtitle for the episode apears in the Description column and clicking on the 'i' button gets you the itunes:summary.

However the Store does appear to have changed its behaviour from what is specified in Apple's Tech Specs note:
http://www.apple.com/itunes/podcasts/specs.html#rss and see diagram

The Description column, as you say, is displaying the itunes:summary for the episode, which in your case is confusing because they all start the same. If you hover the mouse over it you see the full description.

Of course I don't know why this change has been made; like you I'm not sure I think it's a good idea.

You could send feedback to Apple at
http://www.apple.com/feedback/itunesapp.html
(your message will be read but you won't get a reply)

or you could contact iTunes Support:
http://www.apple.com/support/itunes/ - click on 'Other iTunes Store Features' in the list and then on 'Podcasts'.

I am running XP and hovering shows nothing in either the Store or in downloaded episodes. Also, in the downloaded episodes, the "i" button results in a completely blank screen. <itunes:subtitle> is not displaying anywhere in either the store or the downloaded episodes.

I'm not in a position to check on either Windows or the iPhone so I can't comment; are you running iTunes 9? I just checked again running iTunes on 'Tiger' (two OSs back and now obsolete) and it showed all the information just as I described: so it is there.

Do you know someone else with Windows who could check for you (or perhaps you could go to a local library or internet cafe and check yourself) - this would help to indicate whether it's an overall Windows problem or just something on your setup. In the meantime if you have any caches you can clear it might be worth doing so.

Looks like it, doesn't it, but it's all very odd.