Admittedly nothing to do with Cape Town, but I was really impressed by this book, so I thought I’d share.
Recommended by a family friend, In a Different Time: The Inside Story of the Delmas Four by Peter Harris is the story of a group (of five, initially) MK commandos operating in the 1980s. Peter Harris, their lawyer after four were captured and brought to trial, narrates the story. It follows Jabu Masina, Ting Ting Masango, Neo Potsane and Joseph Makhura as they perform assassinations, bombings and other subterfuge; it also follows their trial after they are captured. Theirs was the first trial, I believe, in which the defendants maintained that they were soldiers and should be treated in accord to the Geneva Convention rather than tried in criminal court.
Told in a gripping style, the book is really enthralling. The civil disobedience vs guerrilla warfare debate is a long one which I won’t go into, but this book tells of the warfare side of things and it gives an interesting perspective of that. If I had one complaint about the book it would be that Harris makes some logical conclusions about violent protest, particularly against soft targets that I didn’t follow or agree with.
But, in the end, it’s a very well written. It seems I never find a nonfiction book that I can’t put down; this is a rare counterexample.
The book is available from Kalahari.net.
Secret Cape Town 
Excellent suggestion; I’m going to put that one at the top of my reading queue.
I’d also recommend Mukiwa, one of the canonical memoirs of a white Rhodesian during the time of revolution, and Don’t Let’s Go to the Dogs Tonight which I’m currenty reading and so far is excellent.