Répondre :
I personnaly think that virtual social networks may be dangerous because of the power given to the members. Anonymity strengthens negatively the feeling of impunity behind a screen. As a consequence, some people feel free to express themselves in a way they would never dare to use otherwise. As a matter of fact, a face-to-face relation obeys social rules which disappear in the virtual world. This can lead to dramatic situations of harassment difficult to control. Even if the social networks on the Internet can do a service, I think that the traditional networks are more reassuring. However, new Professional links provided by specific networks like Viadeo or Linkedlin may be much more efficient than a usual network. But those kind of links between people are very much goal oriented and leave no room to power abuses.