Thanks to Mark Oelhert's eClippings, I came across Cory Doctorow's Metacrap article (not sure how I missed it when it was originally posted way back in August 2001 - I've been reading BoingBoing for a long time now...)
Anyway, in the article, Cory attempts to debunk the myth of metadata. He came up with 7 problems (the headings are, I believe, intentionally exaggerated and provocative):
- People lie
- People are lazy
- People are stupid
- Mission: Impossible -- know thyself
- Schemas aren't neutral
- Metrics influence results
- There's more than one way to describe something
I think the points may be quite valid (if a bit overgeneralized) when applied to "user entered" metadata. If Uncle Billy is adding something to APOLLO, he's not likely to be a reliable/consistent/complete metadata tagger. However, if a librarian is tasked with cataloging a set of resources, these rules (hopefully) don't apply, and the structured metadata becomes trusted and valuable.
My gut says Uncle Billy will be better off using the "bags of keywords" approach, because of these 7 points, while The Institution will plug away with deeply nested hierarchical taxonpaths...
Read the article for the goods...