Jonathon Donner has published a survey of research approaches to mobile use in developing countries. An interesting survey with loads of references. See Jonathon’s site for more of his publications.
“In particular, a few kinds of studies seem most popular: those which focus on the mobile as a tool for new forms of instrumental communication and information processing; those which examine mobile’s diffusion ‘by proxy’, comparing cross-national or crosscultural attributes; those which look at the success or failure of particular initiatives to deploy and encourage mobiles adoption, either at the level of an individual project or at the national/policy level, and; those which examine the mobile as new a mediator and enabler of older complex social interactions, mixing global and local, individual and collective in new ways.”
Link: Research Approaches to Mobile Use in the Developing World: A Review of the Literature (168k PDF, jonathandonner.com)