No, not in Africa. You see, "nobody" there has a computer, everybody does have mobile phones. So payment through mobile phones is already common, whereas places in Europe still are implementing it (note: payments with phone for parking is implemented, but bank (micro) payments are not).
So African programmers target those mobile platforms. Now, sl4a is alive. perldroid is a bit dead. As for using the pi itself: Android can be build on the normal raspberry, but you still need keyboards, touchscreen, etc to really be able to do something. Nice idea though. example: http://raspberrypi.citrusperl.com/