As reported today by mydsl.co.za, practically all operators in South Africa are testing or have done successful trials with WiMAX. The most important comment with regards to where and when WiMAX will be deployed - and which is in line with what we hear - is the following:

Telkom has indicated that it may utilize this technology in areas where ADSL is not available, like new business areas without a fixed line infrastructure or in neighborhoods where the copper local-loop length is too long to bring ADSL to residents.
The cellular providers may also look at WiMax as an ‘overlay’ technology rather than a replacement for its existing 3G/HSDPA broadband technologies.