Morten Frederiksen suggested a change to the FOAF snippet in my RSS:

A small suggestion for using foaf inside something like dc:creator: State the above line as

<foaf:mbox_sha1sum
    rdf:value="69e31bbcf58d432950127593e292a55975bc55fd"/>

instead, that way the XSLT/XPath string value of dc:creator is just the name of the person. This can be useful when parsed in a non-RDF context.

A good idea, which I've now implemented.