At the moment, there are 5 iPhone Apps (that I know of) that have developed in South Africa, by South African companies.
While there isn't a huge demand yet in South Africa for locally developed iPhone apps, I think we may start seeing a huge growth with 4 out the 5 apps being launched this year. Keep your eyes on the iTunes store for some great new apps that should be released soon :)
Cramer Media's Mining Weekly - A portal to a very popular South African site aimed at the Mining industry.
http://www.miningweekly.com/. This was SA's first published iPhone app, which is quite popular in its niche.
MobiYze - An app developed by Durban company
Immedia, developed for the very popular Gauteng radio station
YFM. The app allows you to listen to a live streaming audio feed of the station, as well as view latest blog posts from the respective DJ's
News24 - An app developed for South Africa's busiest site -
http://www.News24.com. This app interacts with the whole site showing top stories, sports, motoring stories and loads more. Another cool feature allows you to locate a resturant closest to you and read reviews from the Food24.com site. An awesome app with loads of cool features
MXit - South Africa's popular instant messaging system,
MXit is available on the iPhone. It is a pretty simple app, that allows you to chat to contacts as well as add. Great if you a MXit addict, unlike me :)
DStv Guide - The latest South African app to make its apperance in the iTunes store. The DSTV app allows you to select your favourite DSTV channels, and then get a 7 day TV guide on what is showing. Very basic app, but does the job.
If you know of any other apps, please leave a comment below, and I will gladly add them in.
UPDATE:
Thanks to Nico (@nduplessis) there are another 2 apps I have missed:
Mobile Maps - Developed by South African Mapping Giant AfriGIS, it is a sort of a Google Maps clone, but #failed when they showed me Black & White Satellite images of where I stay -
tax:app - Developed by Peter Pistorius, an app that shows you your tax calculations for the current tax year. Quite a handy app with a distinctive South African flavour (Can't even get it in the US iTunes store)