Recently, Seth Godin made a great point in Personal Branding in the Age of Google that while checking into applicants for a babysitting position he "Googled" each applicant and learned a lot about them through posts they had made on Facebook and other social sites. [A good read on this is Oh, What a Tangled Web Print We Leave, by Brett Popplewell] This is a great example of how people's behaviors on-line mirror their off line identities. At least for those people that use their own identities on-line.