It also got me thinking about the XFN microformat, which is tailored for relationships between people. But what about relationships between people and, say, an organization? Or between organizations and other organizations? Some parameters could still work (you could have an org as a contact, and some people do seem to have crushes on companies) but would it be proper to use a format designed for human relationships for unintended purposes? The alternative answer would be to design additional formats for dealing with these types of relationships.

Edit: As Andy points out, the creation of XPN is being discussed for professional relationships. But still, what about non-human relationships? Is there potential value in describing those? I think so.