The Parental Controls have been improved, are easier to access, are more in-depth, and you can even manage them from another computer. That is, if you've got several Macs in your home, you're all using the same Internet connection, and you've got an automatic local network set up. From your parent machine, you can set up the controls on your child's computer. You can determine with whom they can chat or email, what time the computer can be used on different days of the week, how many hours it can be used, which web sites can be accessed, which applications can be used, and much more.
You can even arrange to have logs created that keep track of your child's activity. For very young children, don't forget to check into the Simple Finder. And, remember, you can set up parental controls not only for another computer, but for any other user of your own computer.