I attended their Beta Launch event in London, where the team set up accounts for a number of the party attendants. Each was given some money to send to anyone in Kenya in order to test the speed and convenience of the service. In each instance, confirmation was received from happy family and friends who received an unexpected top-up to their M-PESA accounts.
A short video recap of the event:
http://www.iamsatoshi.com/bitpesa-launch-uk/