M-PESA (M for mobile, pesa is Swahili for money) was launched in 2007 by Vodafone, and is aimed at mobile customers who do not have a bank account, typically because they do not have access to a bank or their income is insufficient to justify a bank account. The M-PESA system allows customers to:

// deposit and withdraw cash via local M-PESA agents
// transfer money to other users and non users anywhere in the country
// pay bills
// purchase airtime

After success in Kenya the service was also launched in Tanzania in 2008 where there were over 3 million users as of February 2010.

References:

http://en.wikipedia.org/wiki/M-Pesa
http://thecitizen.co.tz/magazines/31-business-week/3032-money-transfervodacom...
http://www.mitpressjournals.org/doi/pdf/10.1162/itgg.2009.4.2.77