Are there any drawbacks to Facebook and MySpace?

I think that teachers should not be adding student as "friends" cause they are their student and not friends, A line need to be drawn some where in the middle of that realtionship and not Crossed,I have to say I would feel like the teacher is favoring all his/her added new friends on that web site, Also lots of personal info. is ped back and forth on these web site to make thinks worse,as for the teacher to feel Intimate with the student, we have so many issue as is for some teachers to allow them self to have a ual realtion with thier student we don't need any more help fro the out side world wide web.thank you, So Yes block or don't allow teachers to add their portfolio to MYSPACE OR