According to insidefacebook.com the percentage of users under 25 years old is 39% (http://www.insidefacebook.com/2010/04/02/facebook%E2%80%99s-march-2010-us-tra

According to insidefacebook.com the percentage of users under 25 years old is 39% (http://www.insidefacebook.com/2010/04/02/facebook%E2%80%99s-march-2010-us-traffic-by-age-and-sex-overall-growth-slower-than-past-months/ http://www.insidefacebook.com/2010/04/02/facebook%E2%80%99s-...) and, judging by their numbers from previous months, falling. Also, your conception of "real users" sure sounds an awful lot like a minority group of users who use it heavily.