If you have a US-issued American Express card and you're planning to attend the Soccer World Cup in South Africa in June, I strongly recommend that you bring another credit card with you.
South Africa is following Europe's lead in requiring a PIN rather than a signature for over the counter credit card transactions. Credit cards issued by US banks don't have PINs. The South African banks are supposed to cater for that by programming their point of sale terminals to recognise a US-issued card (you can readily tell which country a card is issued in from the card number) and not ask for a PIN for a card that doesn't have one. Based on my experience in the last week they've done so for Visa cards but not for American Express (I don't know about Mastercard since I don't have one to test).
Given that Visa is a Soccer World Cup sponsor it all seems a little too coincidental to me. I wouldn't be happy if I was American Express.
Will I be attending a game if I'm here in June? I'm torn between the fact that Australia and USA (I'm a dual citizen after all) have qualified and the fact that I hate soccer!