Yup.
From the US State Department Web Site:
South African law requires travelers to have one (1) blank (unstamped) visa page in their passport to enter the country. In practice, however, travelers may need more than one page as there have been instances in the past of South African immigration officers requiring travelers to have two (2) blank pages. You are advised to have at least two blank pages; one for the South African temporary residence permit sticker that is issued upon entry to the country, and an additional page to allow for entry and exit stamps for South Africa and other countries to be visited en route to South Africa or elsewhere in the region.
Travelers without the requisite blank visa pages in their passports may be refused entry into South Africa, fined, and returned to their point of origin at their own expense. South African authorities have denied diplomatic missions access to assist in these cases.
When I traveled there I was advised to have two consecutive blank pages.