I saw a post recently on Controlled social networking for student collaboration. One of the comments lamented not having the head count to install technology to control Facebook access by students.
Frankly – as a data security and compliance consultant who does a lot of work with corporates in social networking (both on the application side and security side), I  would not use technology as an excuse for social media abuse.
This is a cultural and behavioral issue similar to any other content abuse issue. It starts with education: at home, in the school and with parental and teacher role models.
Current definitions of privacy are changing. Regulatory definitions of privacy used by legislators in the credit card and HIPAA compliance space do not seem to be relevant for under 25 users of Facebook – who are happy to disclose pictures of themselves but very careful about what they show and who they would share the media with.  I believe that as social media becomes part of  the continuum of social interaction in the physical  and virtual worlds, privacy becomes an issue of  personal, discretionary disclosure control.
To this extent, it seems to me that we are moving rapidly towards a new generation of social networking that is much closer to what happens in the physical world – centered on individual perspectives, one person, their friends, selective disclosure and information leakage by word of mouth not by IP protocols, social media and public access Web sites like Facebook.
But – that is already another technology kettle of fish.