Thinking about how recent social networks have shifted from topic-focused (bbforums, reddit, image boards) to person-focused (tumblr, twitter, etc.) where rather than subscribing to a topic and space where anyone participates in the conversation that way, you subscribe to a specific person and everything that they have to say. on twitter nothing you say will be seen unless people are following you; or if you post to a hashtag which is, let's be honest, not commonly looked at.

@shel @lifning I remember seeing a presentation from Google when they were launching Google plus that mentioned this. It said the Web used to be page or site focused, and the social web is person focused.