Mark Paschal has written a very nice detector which generates static RSS feeds from roundup issue changes:

http://markpasc.org/code/rsswriter/

There are a couple of advantages to this approach over TemplateBasedFeedGeneration:

1. The file is static so you can host it from a normal web server, so you could have a public feed and a private tracker, or more commonly, the static feed could withstand the battering of thousands of badly behaved news readers. (This would be a good spot to rant on about people who set their news reader to poll sites every five minutes.)
2. A detector is told what has changed (and can be made to only look at specific events), so it can produce a good summary of the changes.

There are also a couple of disadvantages:

1. Since the feed is statically generated from a pre-defined set of criteria you can't add more custom feeds without editing the script generating the feeds. This means that it's harder for users to get ad-hoc feeds on particular issues.
2. The feed is only generated when the issue is changed, so if you want the feed to include information from other items it will only be a snapshot of that information. This might not suit users in situations where the issues themselves link to a lot of relevant information (of course you can just hook in to the other item's change events).

If you get:

   File "/home/roundup/trackers/support/detectors/rsswriter.py", line 141, in writeRss 
       from nosyreaction import determineNewMessages 

   ImportError: No module named nosyreaction

just copy the function determineNewMessages() from nosyreaction.py to rsswriter.py and comment out the line:

   from nosyreaction import determineNewMessages