Has anyone faked the User-Agent to see more?
UPDATE (2007-06-29): Now that the iPhone is out, the page (on a real iPhone) has the title "Device Error page" and the body text "If you'd like to view an RSS feed, just enter the feed URL directly into Safari's address bar."
When you do that (e.g. http://jtauber.com/atom/full/) it actually redirects you back to http://reader.mac.com/mobile/v1/{{the feed url}}