While at eTech, I attended a number of "social software" sessions. One thing I heard was a persistent call from folk like Marc Canter for all the vendors to support something called FOAF. FOAF is a standard for "Friend of a Friend" files, and is an attempt to make machine readable information about people, groups, companies, and other online resources. In particular, it is focused on representing the information that you might typically put on your personal home page in a form such that meta-data tools can interpret it.