It has already kicked off but it's in pilot phase so demerits wont be deducted as yet until the trial run is over with. They have not specified when this will be. Probably towards the end of the year though.
It looks like there is a pilot in Johannesburg and Tshwane. The official start will be November 2010. They say drivers won't be penalised.. I am not sure if the points people get in the pilot will carried forward in 2010. That doesn't still seem clear to me from the AARTO press release on the RTMC website..