Oh, fer Chrissakes!
I can recall being a 12 year-old in 1981 and discovering my dad's stash of Playboy and Penthouse magazines. Yeah, I was looking for them and when I found them tucked away (unlocked) in the back of his closet, it was like striking gold!
I stole them all and distributed them equally to all my other 12 year-old friends.
Somehow, we were not warped from the exposure.
When did we suddenly discover that if a child sees a photo/movie of carnal copulation, he or she is going to be damaged for life?
Probably by the same person that walked in on their parents doing it. Which can be a frightening experience, unless your mom is like Christie Brinkley and then, well... you've got a whole lot of Freudian issues that are going to beset you.
But back on topic, I don't see how they could put that genie back in the bottle. As someone else mentioned, man has been looking at, and creating, sexual "art" since the beginning. And with the Net, I can't see how they could regulate it without some serious invasions into every packet that traverses the net. And that right there opens up a whole nother can of worms.