Friendship, Trust, Interest, and Reciprocity

Very interesting post from Moshe Z: What is Friendship?

Image via Wikipedia

Basically on how Friendship, Trust, Shared-Interest, Entertainment-Value cannot be conflated, and, even considered separately, are not always reciprocal. (But does that in fact cover the whole range of positive relationships in social networking? Maybe we get a pretty good model if we also add that people wear different "hats": hobbyist, professional, political, fan, activist, ...)