Its taken several weeks of tearing what little hair I have out, but finally managed with Jonathan Furness' help to make an RSS feed work inside a Plone page. For a sneak preview of Ultralab's web site go to ww3.ultralab.net and click on the news tab to see what I mean...
All this should be dead easy, but in our experimentation we had installed several different copies of Python, the underlying language for Zope/Plone, and only one would do when it came to installing the Feedparser module - the copy inside the Zope path. To make it work this copy of Python had to be explicitly referenced in the install command.