Richard Ling's latest paper is very pertinent with regard to sociocultural aspects of SMS usage: The socio-linguistics of SMS: An analysis of SMS use by a random sample of Norwegians by Richard Ling:

a corpus of SMS messages gathered from a random sample of 2003 Norwegians. The data was collected in May of 2002 by telephone. Along with demographic, behavioral and attitudinal questions associated with mobile and SMS use, we asked the respondents to read (and where necessary, to spell out) the content of the last three messages they had sent. This resulted in a body of 882 SMS messages from 463 (23%) of the 2002 respondents. What does all this tell us about the socio linguistic nature of SMS? The paper examines various aspects of SMS production including themes in the messages, frequently used words, word and message length, use pf punctuation, capitalization, salutations and closings, etc. A general finding is that the culture of SMS lives among younger women users. In spite of the fact that men were early adopters of mobile telephone, it is among these women that the great motor of SMS lives. Women, and in particular younger women, seem to have a broader register when using SMS. They use them for immediate practical coordination issues and also for the more emotional side of mobile communication. In addition, their messages are longer, have a more complex structure and retain more of the traditional conventions associated with other written forms than men. This competence is also extended to telephonic communication.