I think if a social networking site got "social circles" right, it would take off.<p>I think the main problem that others have pointed out, is that you typically have a persona that you reveal to different groups of people and you typically only want those groups to have a specific view into your life:<p>* Family - you are an upright person that loves grandma's pumpkin pie.<p>* Distant friends (coworkers) - you are a hard worker that occasionally is interested in backyard BBQs.<p>* Close friends - they know you are really a drunk.<p>* Intimate friends - they know you are really just a big kid.<p>* Internet friends - know you really have a thing for fishnets.<p>Point is, a social network really needs to successfully tackle this issue. If they can do that, then they'll be able to fold facebook, linkedin, twitter, et al all into one site.