Social Networking - good or bad?

I have both a myspace and a facebook page. I have some friends who only do one of them so I have both to keep in touch. I find it a convenient way to get in touch with old friends and to communicate with current ones. I did not have my page private at first and got some strange and unwanted requests. My page is private now so that only my friends can see my page. I especially like to change the song and background to my page and to add pictures.
I do think that it can be used as a tool to prey on the vulnerable. I am aware of the safety precautions one should take with such a tool but I am afraid many others are not and could be taken advantage of. Myspace has gotten somewhat of a bad rap for this and have tried to put in more safety features.
I have looked at many library myspace pages and can see that they can be used as a way to get information out about the library out to its patrons. I have also seen that many of the friends on these myspace pages are authors trying to promote their books. I am still going back and forth on doing one for the teens here (I already have a blog). Many of the "teens" that show up to my programs are not 14 and over so they would not be allowed to have a myspace page. We'll see!