A little research...

Wikipedia: "A social network service focuses on building and reflecting of social networks or social relations among people, e.g., who share interests and/or activities. A social network service essentially consists of a representation of each user (often a profile), his/her social links, and a variety of additional services. Most social network services are web based and provides means for users to interact over the internet, such as e-mail and instant messaging. Although online community services are sometimes considered as a social network service in a broader sense, social network service usually means an individual-centered service whereas online community services are group-centered."

"Interpersonal communication has been a growing issue as more and more people have turned to social networking as a means of communication."Benniger (1987) describes how mass media has gradually replaced interpersonal communication as a socializing force. Further, social networking sites have become popular sites for youth culture to explore themselves, relationships, and share cultural artifacts"A Privacy Paradox Many teens and social networking users may be harming their interpersonal communication by using sites such as Facebook and Myspace."

Mashable: "internet users are far more likely (45%) to visit a café or a coffee shop than people who don’t use the internet...the myth that frequent internet users hang out mostly at home is also busted, as people have started using it many public spaces, such as libraries, bars, coffee shops, restaurants and the like."

"online activities such as social networking, sending e-mails and blogging can lead to larger, and (perhaps even more importantly) more diverse social networks"

Pew Internet and American Life Project: "Social media activities are associated with several beneficial social activities, including having discussion networks that are more likely to contain people from different backgrounds. For instance, frequent internet users, and those who maintain a blog are much more likely to confide in someone who is of another race. Those who share photos online are more likely to report that they discuss important matters with someone who is a member of another political party. "

"Challenging the assumption that internet use encourages social contact across vast distances, we find that many internet technologies are used as much for local contact as they are for distant communication."

"Some have worried that internet use limits people’s participation in their local communities, but we find that most internet activities have little or a positive relationship to local activity. For instance, internet users are as likely as anyone else to visit with their neighbors in person. Cell phone users, those who use the internet frequently at work, and bloggers are more likely to belong to a local voluntary association, such as a youth group or a charitable organization. However, we find some evidence that use of social networking services (e.g., Facebook, MySpace, LinkedIn) substitutes for some neighborhood involvement."

Google Xistence Mock Video by Australian web designer Philipp Drössler: