Richard Mac Manus connects WikiLog node links and Back Links with other OntolOgy/TaxonOmy attempts.
He doesn't note that if you go to User Options and turn on "Show page hierarchy" you'll get a slightly different view - the chain of generations of pages whose creation led to the current page. (Hierarchal Structure)
the key meta-question is "what's the point?" - what benefit do you hope to get by clustering your WebLog entries?