Facebook’s stated goal is to model the social graph. By this they mean that they want to model the relationships between all people. If you have a friend in meat space, they want to model it in software. But it has become increasingly clear that Facebook is modeling personal relationships, not relationships based on attention. That’s the crucial difference between Facebook and Twitter at the moment.
Insightful post by Joshua Porter about the difference between symmetric (Facebook) and asymmetric (Twitter) relationships.






