So here’s a surprise – FireFox 3.0.1 can’t handle RSS/Atom feeds that have a port number in the URL. The problem stems from the fact that it uses a custom feed: protocol instead of just working off of the mime-type of the content.  So if you visit http://www.example.com:10038/ and it provides an RSS autodiscovery link that points to /feed/, FireFox will try to go to feed:http//www.example.com:10038/feed/.  Note the missing colon after http.

What’s even more odd about this is that the actual request it sends is for the URL: http://feed://http//www.example.com:10038/feed/.  Bizarre!