Brian Solis give us here a great article focusing on demographic results of social network usages.
Take a look at the examples he shares on his article "Revealing the people defining social netwroks".

Remember our last posts with the statistic results of Facebook or Twitter and other online communities: people are no more individuals they are a tribe which get fully involved into a new relationship with brands and social communication.

Yes it's true...mondays are difficult (in general)...it's monday...and I have to go back to work...