Identity is a something that people grapple with all the time but don't really get. Consider for a second looking out of a car with the windows rolled up. When you do this you sometimes see your reflection along with the outside world at the same time. Identity is a bit like that. Who you share as is just as important as who you share with. This is something that both facebook and google plus get wrong. Have a look at how Sacha Baron Cohen has various personas. What he can do as very different from what he does as AliG even though in many cases the audience is the same. Twitter gets it right because they are the only service that allows multiple handles, monikers and they are essentially the only ones right now who allow(or even encourage) you to have a online presence that is completely divorced from real life. This is important because people have stereotypes in their head and if your name or picture reinforces those, you are already in a box, out of which it is very diffic