At the recent Google conference in Cape Town, they made it very clear that they see mobile phones as the primary platform to access the internet in Africa, now and in the future. They're investing lots of resources and money to try and stimulate the mobile web. It's the land of opportunity for developers if you can think of a good idea. Interesting they even said outright that they don't see Android / iPhone apps as the answer. They see mobile web applications as the answer, because they're cross platform and easy to update. But they assume 24/7, cheap connectivity. I think it will be a while still before we get there in SA. For now Ithink the apps based model (that you can use offline) is a good solution for SA.
Now if only I can get off my ass and write a few of the Android apps I have ideas for. And it will help if Google can finally bring paid apps to the SA Android market.