Rands, on his way to discussing what one's bookshelf says of their psyche, gives a succinct summary of social information sharing:
A quick scan of my Twitter stream reveals that apparently real names have replaced nicknames as a means of identification, but this doesn’t change the fact that never in our history have we known more people less. We spend the day swimming in the 10% of the information that others have deliberately chosen to share with us and while it is overwhelming in volume, it’s only so because there are so many people… who are actually sharing very little.
I think 10% is pretty generous.