Teens do not consider a lot of their electronic texts as writing

The state of writing among teens today is marked by an interesting paradox: While teens are heavily embedded in a tech-rich world and craft a significant amount of electronic text, they see a fundamental distinction between their electronic social communications and the more formal writing they do for school or for personal reasons. 85% of youth ages 12-17 engage at least occasionally in some form of electronic personal communication, which includes text messaging, sending email or instant messages, or posting comments on social networking sites. 60% of teens do not think of these electronic texts as "writing."
http://www.pewinternet.org/press_release.asp?r=301

Writing, Technology and Teens
http://www.pewinternet.org/report_display.asp?r=247

Study: Teens say e-text isn't writing (C|Net)
http://www.news.com/8301-10784_3-9927251-7.html?part=rss&subj=news&tag=2547-1_3-0-5

Informal Style of Electronic Messages Is Showing Up in Schoolwork, Study Finds (NYTimes)
http://www.nytimes.com/2008/04/25/education/25writing.html?ref=todayspaper