Xen Mendelsohn has an interview with Nick Wright:
The relationship between youth and their mobiles is not necessarily based on being fun, cool, or entertaining. Its a key social tool employed in the dynamics of the peer group. Youth consume mobile products – as they do others – to make statements about themselves and their relationship with their peers.
Self-expression is such a key aspect of young peoples lives that they would rarely choose a non-branded alternative over an identifiable brand. 98% of teens for example would choose a brand/logo designed T-shirt over a plain one.
Mobile is most importantly a symbol of belonging to a group, both as a physical product (you must own a phone to be part of our group) and its communicative possibilities: texting is essential to youth not because of the content (very limited) of the texts themselves but because each text is a reaffirmation and a reminder that Im with you.