http://feeds.fubarpodcast.at/fubarcast seems to be the feed which you have registered at the iTunes Store.
The iTunes image in this feed is http://fubarpodcast.at/wp-content/fu_ked_long.jpg . This is the image I can see at the iTunes Store page when I follow the link in the first post of this thread. Is this the old one?
The RSS image is currently this file http://fubarpodcast.at/logo.jpg . It is also 1400x1400 pixels while it should be 144x144 px. Is this the new image?
The description of the feed is "Pretty much foobar" and the iTunes:subtitle as well as the iTunes:summary is "fu'ed up beyond all recognition".
If this summary and subtitle are not the correct ones although you have already modified the values then you have probably not modified the correct settings (page). Or maybe the content of http://feeds.fubarpodcast.at/fubarcast comes from a cache memory.
Or your current podcast feed has a different URL now and iTunes uses still the old one.
However the iTunes Store page shows what one can see in the XML code of the feed and also seems to be up to date (it shows the episode 29c3 Tag 1).
Where did you change the settings?
Is this feed a podPress Feed? Or a category feed? Or simply the default post feed of WP?