@mark, not sure who is working on ethiopayment, but i looked around and looks very unsecure for transactions. This is just my personal observation, so from a purely technical perspective. Its a good start but has a very long way to go.
@ayalew, a lot of people have a very wrong sense of security. Although transacting money offline has its own advantages, in reality it is less secure and has a lot of flows. Like any technology, the implementation of such a system has its own ups and downs. I work primarily on such applications abroad and there are ways to mitigate the risk, and when it comes to a country like Ethiopia, different business models can/should be used. For example, paypal solutions only address people who are are online and mostly banked. For Ethiopia, you probably want to deal with the unbanked society and so you may be inclined to look into physical agent networks or use existing ones like the post office to create that virtual sense and also maybe use SMS/IVR for processing payment while keeping the online one optional.
Note that when talking about such solutions, you should think about the many different ways it can be used, paying your bills, topping your airtime, sending/receiving money, processing bank transactions. These are just from a personal perspective, merchants and businesses will see a whole lot of uses for such a solution.
Generally speaking, a lengthy discussion might be needed if you actually want to know what would work for Ethiopia. But one way or another, it is needed and would be successful with the right technology and business model.