I’ve been thinking about this in terms of the .net community, but I’ll explain it in terms of the Wondergeeks:
Let’s use Amy. Amy would list Jeff as a spouse, Heather as a colleague [since they did work together back in the day], Andy as a friend [as well as many others of us, certainly], and other folks that she’d simply just met as “met” or “acquaintance”. On the other hand, I could not list Brad as someone I had met, because we haven’t.
I think that the idea’s pretty interesting, in some weird Six Degrees-ish kinda way. Is it very useful? No. Does it have to be useful? No.