There was a recent comment made on my post called It's Never Been Easier To Spy On Your Children, wherein a parent asked if there were any websites or forums that might help her to parent and protect her tech-savvy teen without taking away his administration privileges.
Admittedly, I am not an expert on this subject. I know a little bit about internet filtering, and have recently learned about accountability software, which, although it is intended for self-use by adults, may be an interesting approach to teaching older children about disciplining themselves to visit appropriate online content.
I don't know enough to address the subtleties of this particular issue, since it may (or may not!) include brand new restrictions on a child who is used to none, or have something to do with a child who is hiding things from his parents, so here is the point wherein I pass along another blog.
Teens Today with Vanessa Van Petten has a great post/advice column that addresses reviews of specific parental control software. It includes links.
I do not know of any specific forums that address this issue, although I think they would be interesting. Readers, if you know of any, please comment!
I believe that any parent's best bet is to get educated. Learn just a little bit more than your child, and try to keep the balance that way for a long, long time.