Michael Arrington and Dave Winer are requesting that Facebook add more options to their “How I know you” feature, where you indicate the type of relationship you have with another person and how you met. I want the feature to incorporate the XFN Microformat.
XFN is a way in HTML, using the rel attribute, to denote the type of relationship that you have with someone. Some examples of possible attributes are friend, co-worker, neighbor, crush, muse, parent, child, and many others.
In Facebook, if someone chooses they know eachother because they work together, whenever the two user’s friendship is represented in HTML it should use the rel=”co-worker” attribute.
Somehow then I’d be able to programatically take the relationships I have from Facebook and mash them up with my non-Facebook XFN marked-up relationships or bring my non-Facebook XFN marked-up relationships into Facebook.
Oatmeal Stout - Justin Thorp's blog 