An interesting piece on age restrictions in World of Warcraft...

For environments like Second Life and World of Warcraft, think for a minute about the benefits of an age restricted server. On the adult side of things there would be less interference from age related and maturity issues*. Things like talking in l33t s93ak, the social issues of growing children and teens, and not having to worry about age appropriate content/conversations would be a very good thing for many of the adult players out there.