You cannot talk about mobile money without talking about M-PESA. M-PESA has become so successful it is being used as a model by other countries who want to set up similar services. In 5 years time, M-PESA has over 15 million customers and over 35,000 agents across the country. M-PESA transfers more money domestically than western union does globally, and transacts about 20 per cent of Kenya’s GDP. But you already know that.
Much has been said and written about why M-PESA has been so successful. CGAP (link) blogged about why M-PESA has become so popular in Kenya. Another study (pdf) shows the key factors that made M-PESA a success story.