Introduction to vocabularies; Shared categories for IA

I've got two threads here. One is a link to the Getty site and the second is a discussion about a controlled vocabulary for IA.

Getty introduction to vocabularies
I've long been intrested in the description of objects of art and several years ago delved into the literature of cataloging art work using the Getty and Visual Resources Association categories. I came across a section of the Getty site that talks about controlled vocabularies and the value of their use in describing works of art in networked environments. Should be valuable to people interested in learning about or selling the value of indexing with a controlled vocabulary. This is what the site aims to demonstrate specifically:

    1. Vocabularies can be used as "assistants" in database search engines, creating a semantic network (or roadmap) that shows links and paths between concepts. When querying a database, users can follow these paths composed of synonyms, broader/narrower terms, and related concepts to refine, expand, and enhance their searches and achieve more meaningful results. When used as a search assistant, a vocabulary is a powerful knowledge base -- linking searchers to information from both structured and unstructured databases.
    2. Vocabularies are sources of "standard terminology" for use in the description, cataloging, or documentation of cultural heritage collections. Vocabularies often reflect consensus of opinion within a community, that is, by answering the question - "How do we talk (or write) about this partiuar subject area?" In doing so, vocabularies become valuable tools for professional catalogers and documentation staff who need to establish consistent access points.

    Vocabularies play a critical role in the larger movement to create and apply standards that will improve access to cultural heritage information. This work requires creative collaborations among nations and disciplines in ways that have not been attempted before.

Controlled vocabularies for IA
The last point about improving access to information is relevant to our discipline. Many of us struggle when trying to exhaustively search the IA sites on some specific topic and find ourselves at a loss because different sites might describe (categorize/classify/index) that topic differently and our search tools might not help lead us to the place on all of the IA sites that mention that topic. A few people with popular sites have felt this pain with me. I have had discussions via email with a lot of these very smart people in the last couple of months. So, on IAWiki Eric is leading a discussion about the concept of SharedCategories and the value of sharing of indexing/classification schema. Please go there and add your thoughts.