'Children and their Changing Media Environment' was a comparative, European research programme (12 participating countries, 1996-99) on 6-16 year old's media uses, also cmc and phones. All national teams did large scale surveys combined with qualitative studies on the same research-design. The comparative project is written up in "Children and Their Changing Media Environment", edited by Sonia Livingstone and Moira Bovill, Lawrence Erlbaum 2001. Besides there are numerous books and articles on the national findings from each participating national team. You can search on the national team members from the information in Sonia's and Moira's book. The stats, especially on cmc and mobile phoning might be a little out of date even if the analysis are valid, but I know that most of the participating researchers have continued researching along the tracks of the European project.

My own newer studies show that new media, new forms of communication are integrated in everyday media uses - you don't drop other media (in general) when new one are accessible, but broaden the choice of possible media. Each media (form) serves a particular need/practice. Denmark is one of the countries with largest penetration of mobile phones, also among children and young people - with a huge use of sms.