Facebook and teens

I just posted this, ironically enough, on my personal Facebook page: Do/would you let your teen have a Facebook account? Would you monitor it? Here I will expand a bit. What teens sometimes choose to post on their Facebook pages tells quite a lot about them, and it might be more than you want. I can imagine that those who wish to keep up a RW image would find much of what their teens go for in public rather embarrassing and possibly detrimental. I do know of parents who do allow their teens internet access, accounts, etc. but then follow their trail through various accessories that would serve as virtual nanny cams on their kids. Experiences and views on this, anyone?