i had a brief fascinating chat with the author of PeriPeri, a testingground rdf-backed miniwiki, earlier this evening and ran across this entertaining and possibly pertinent page on faceted classification / unplugging hierarchies etc. maybe old news?

http://www.usemod.com/cgi-bin/mb.pl?FacetWiki

FWIW re Habituation, i have found distinct fields and purposes for Category and Locale to be invaluable, but the category foo / category foo index distinction to be a bit painful and disjointy to unaccustomed users...

zx