Knowing how teens use social media is useful to not only youth services librarians, but all librarians - after all, teens tend to grow up and access academic libraries or special libraries someday. Even more important to keep in mind - they may turn into decision-makers who have the power of increasing or decreasing funding, space, and missions for future libraries. Along those lines, you might want to check out this report:

The Pew Internet Project released a new report today on Teens and Social
Media. The report is available at
http://www.pewinternet.org/PPF/r/230/report_display.asp.