As I posted on Orkut.com about Categorizing RSS Entries:
Since this is the Semantic Social Network community, I think semantics is the answer to this one. :)
The software should be smart enough to group author-designated categories according the meanings of the words or phrases used to describe them.
I also like the way the del.icio.us social bookmarking tool enables user to specify their own tags, which others members of the (social) network can browse. Combine this with a semantics engine and an Amazon-style "the members of your FOAF network categorized this RSS feed as _________ and they also subscribed to _____________" and you have a fantasic collaborative social semantic categorization system (a CSSCS). ;)