MIT's Technology Review has published a series of articles on the rapid and extensive growth of mobile devices. See this link for the article, which has links to other interesting facts, like where the money is in mobile technologies.
Recall that the cellphone has just turned 40 years old and that not long ago, everyone thought of computing as PCs - personal computers. Again, my favourite quote from Manuel Castells applies:
"The key feature in the practice of mobile communication is connectivity rather than mobility. This is because, increasingly, mobile communication takes place from stable locations, such as the home, work, or school. But it is also used from everywhere else, and accessibility operates at any time. So, while in the early stages of wireless communication it was a substitute for the fixed-line phone when people were on the move, mobile communication now represents the individualized, distributed capacity to access the local/global communication network from any place at any time. This is how it is perceived by users, and this is how it is used. With the diffusion of wireless access to the Internet, and to computer networks and information systems everywhere, mobile communication is better defined by its capacity for ubiquitous and permanent connectivity rather than its potential mobility (Castells, Fernandez-Ardevol, Qiu and Sey, Mobile communication and society: A global perspective. Cambridge, MA: MIT Press, 2007, p. 248) (emphasis added)."