The to site script runs once, some times fails fetching a site and just continues. Data is based on people using the Alexa toolbar. Detection is open source, so it's easy to circumvent if you don't like your site identified. So these aren't seriously rigorous ranks, but still worth it for fun.
That being said, I also made a mistake in reporting Drupal growth last month. We have three months' data now. The fist month we detected 99 Drupal sites in the 13 000-odd sites checked. The second 86 and this last month 87.
Joomla!'s last three months' data was 332, 304 and 283, so shedding top sites notably. Wordpress' was 763, 730 and 693 and it's loss of top sites rather surprised me.
Congratulations to itbgt and their IT team who takes top spot with nwu.ac.za (still serving on www, I see ;-).
Taking second is westerncape.gov.za with dubois and the directorate e-Government for Citizens behind it, also still serving on www.
And third position goes to whoswho.co.za with pretty no-www serving but without anyone that I saw here on g.d.o. having reported as the creators of the site.
Help improve South African statistics for the top list by installing the Alexa toolbar on your, your friends and your clients' computers.
I'll come site down to draw us the full list of 87 Drupal top sites in South Africa from the database a little later today. In the mean time, I build a quick one-day site to learn a bit about responsive design and using XPath for feed aggregation on the public holiday just past. Keep up with Drupal while at the gym or driving by listening to these podcasts: drupal-podcasts.burtronix.co.za.
Do we have more of the top 50 authors and collaborators on here? Should I enhance the top 50 sites list to link to users on g.d.o. that took part in their creation if they volunteer such identity information here?

Comments
Forgot to add the link to the top site page ;-)
top-sa-drupal-sites.burtronix.co.za
Here's a few more (after 50)
50-87 available, but g.d.o. triggers a spam block if I try to post so many domains, probably seen as spam links. So use my contact form if you want to request the additional links and I'll e-mail them to you (you'll probably still have to dig in your spam folder then).
Honourable mentions
It would probably be easier if you put the additional sites on their own page and include it as a link on the report.
As for linking to profiles that might be hard in some cases take #49 Octangle for example. The site was built by eConsultant but almost a dozen different people have worked on it over the years.
Perhaps using the d.o profile links would be a better alternative e.g. https://drupal.org/profile/profile_current_company_organization/Acquia
As for who built what I know the following are managed by eConsultant:
gcis.gov.za
penguinbooks.co.za
octangle.co.za