Thanks to Simon Rippon’s urging and help, two different kinds of comment feeds have now been set up.
Comments feed for the whole bowl of Soup: http://peasoup.typepad.com/peasoup/comments.rdf
The feed seems to be working well with Google Reader, NewsGator, Bloglines, Google personal homepages, and with the Firefox browser (and its Live Bookmarks). (I seem to be having some trouble with the feed from My Yahoo.)
Comments feed for each individual post: At the bottom of each individual post on which someone has commented, there is a link to the feed that allows you to "follow this conversation by subscribing to the comments feed for this post."
(If you’re unfamiliar with RSS readers/aggregators, you can copy the feed links and follow your reader’s directions to Add a Feed. If anyone has some better tips for keeping track of feeds, by all means, let us in on it.)