Parents should monitor their children's Internet activity very closely, although it is going a little far to suggest there should be laws for minors on the Internet. Teenagers have always and will always participate in adult or illicit activities against the wishes of their parents, but these things can be carefully monitored from home now.
Netiquette for teens should be different than the rules are for adults, because they are still in the developmental stages of their lives and think much differently. Their brains aren't completely formed yet. But, really, there is no such thing as netiquette. It's something very abstract and doesn't have real meaning.
I think when you are younger you can be more relaxed and use more slang when communicating online, most young people are often talking to many people at once and need a fast way of communicating, when you are older you are likely talking about more professional topics at a slower pace so the conversations should be more formal and more well put together.
Adults can deal with each other in ways that differ than that of teens. We can handle bullies and other issues, with a grain of salt. I know everyone can't do this,but netiquette is something that can be lost on adults. The fact is children should stay in their world and the adults should stay in theirs.
I think that as long as nothing illegal or criminal is going on, then netiquette rules should be the same for everybody regardless. I do not think that adults should be allowed to behave differently than people who are younger in age. I think that manners and behavior should be the same.