Sources: SABC (South African Broadcasting Corporation) and South Africa public holidays (qppstudio.net). Government spokesperson, Themba Maseko, has announced that the South African government had declared June 24, 2008, as the national day of mourning for the victims of the xenophobic violence, but that that day would not be a public holiday.
Update (24-June-2008): Earlier today, Government spokesman, Themba Maseko, announced that the national day of mourning scheduled for today, had been postponed "to enable more planning to be done and to ensure that more people participate in events of the day". He added that the government would set a new date soon.