My iPhone 4s 32 GB is faulty, it's just 5 days old but I only just noticed that the focus does not work. My wifes iPhone 4s is fine, when I press her 4s screen the screen shows it changing focus, it goes blury for a sec then hers gets nice and sharp. Her working 4s camera makes a very quiet sound from the camera when focusing (put it right on your ear). Note this autofocus sound on the working 4s is not from the speaker, it sounds like a very small motor in the device.
Yet mine 4s does not change focus at all, its like the focus motor is stuck. The faulty 4s camera makes no sound within the device when it tries to autofocus.
The faulty 4s gets very hot if I leave the camera active.
Very disapointed in my iPhone 4s camera as my old iPhone 3 takes better pictures (Yes I still have my iPhone 3 :-)). I will take the 4s back, but I hope its not a long turn arround for repair (as it's <7 days old)...