Personas
It's quite bizzare, a couple of days ago I posted a blog about the fact that social sites need to embrace the way that people share different things with different groups in different ways. While I feel that google+ circles feature goes some way towards this, I don't think it goes far enough.
Social Media with personality
http://goo.gl/gux9R
It will be interesting if this is the first step towards a social web that acknowledges our different "personas" and means we don't have to create multiple business, home, friend accounts etc.