If we feel there is a need to distinguish between "the primary external resource (which is possibly being commented on in the summary or content of the entry)" and "other resources related to this entry", then we should invent a new rel value to distinguish them.
|rel="alternate"| - This is the permalink for the complete entry |rel="about"| - The entry is about this link. |rel="related"| - This link is related to the link the entry is about |rel="via"| = This is the source of the link the entry is about
-- Anne van Kesteren <http://annevankesteren.nl/>