Pew Research has just published results of a study into American teens focusing on video games and civics, entitled (oddly enough) Teens, Video Games and Civics. Almost all teens game, but few are into MMOGs and virtual environments.
Overall, 97% of teens (99% of boys, and 94% of girls) were gamers, with 80% of teens generally playing five or more different genres of games. Racing, Puzzle and Sports games topped the list (with 74%, 72% and 68% respectively), while MMOGs like World of Warcraft, et al came in at second-last place with just 21% and virtual environments (Second Life, Habbo Hotel, and so) in last place with only 10%.
The five most popular games among teens were Guitar Hero, Halo 3, Madden NFL, Solitaire, and Dance Dance Revolution ranging in ratings from E for Everyone to M (Mature).