If you haven’t seen it yet, there is some deep information provided by the French Association of Mobile Operators on evolving French behavior and attitudes towards their mobiles. You can find an English translation of the summary over at Experientia.
When I was writing Designing the Mobile User Experience, I investigated a wide variety of such studies. Mobiles and their roles in gossip and social grooming, A Tale of Three Cities comparing social behavior in London, Paris, and Madrid, and so forth. You can find some of this information in the book. This type of study is ongoing, and provide ever deepening understanding of the ever evolving social experiment that mobile phones are providing.
Just to ramble a little bit, I was just listening to a lecture by Sir Jonathan Sacks, in which he talked about four major revolutions in communication: invention of writing, invention of alphabets, invention of printing, and invention of Internet (mostly as person-to-person communications). He asserted that the Jewish faith was revolutionized by the second, the Christian faith by the third, and the Muslim faith is currently undergoing a revolution in the fourth. I find myself wondering whether mobile phones as communication are part of Internet, or are part of another revolution. If the latter, what faith might be revolutionized? Mormons? Buddhists? Hindus? (the first seems odd but is to one measure part of the same line of faiths outlined by Sacks).