I'm working on a class website, and on it there is a Myspace/Facebook disclaimer to let students and parents know that I will not add them as friends on either account. I don't know... it just doesn't "smell good" to me. As a young teacher, I don't want my students to think we can be buddies. . I think for more older or more experienced teachers it is probably fine. My accounts are private, and there isn't anything I've posted that is inappropriate. However, I can't control what my friends post on their (often public) Myspace accounts, which the students would have direct links to from my site.