Mobile phones are revolutionizing business activities in many emerging markets. Given the often poor availability of landlines, the dramatic growth of the mobile phone sector has been a godsend for developing countries. Here is an interesting story from The Economist:
http://economist.com/blogs/babbage/2010/08/jugaad
For a technical study on the impact of mobile phones on the agriculture sector, see
Socio-Economic Impact of Mobile Phones on Indian Agriculture (February 2010) by Surabhi Mittal, Sanjay Gandhi, & Gaurav Tripathi
http://www.icrier.org/pdf/WorkingPaper246.pdf