Ok, so we already knew that. But this comScore report confirms that if we want to reach younger audiences, the internet is the place to do it: "U.K. Teens and Young Adults Spend 24 Percent More Time Online Than the Average Internet User".
And, "The comScore study revealed that many of the sites with particular appeal to the 15 to 24 age segment fall into the Social Networking category, including Facebook.com, Bebo.com and Tagged.com. Other properties with strong teen and young adult appeal include ARTISTdirect Network and Alloy, which are news and entertainment sites."