RDF as it applies to field structure in core

KarenS has kicked off a discussion on CCK field structure for core in D7. It's also webchick's itch of the week.

David Strauss is already commenting, and has experience in RDF from the Internet Archive, but it would be good to have other experienced people giving this the once over. Since these fields are likely to be a major way that people "transparently" create subject/predicate/object relationships, we better get this right (and performant, working on shared hosts, etc. etc.).