I wanted to take a photo of Graecyn yesterday with my iPhone 4S. I launched the camera app from the lock screen. The familiar shutter image appeared but didn't proceed any further through the process. I tried again and again, quitting a relaunching, but nothing happened.
I did a hard reset, tried booting into different camera apps I have on my iPhone, but each resulted in no joy.
I did a web search and found that this was an experienced problem with some users. I went through the basic restore steps, even wiping my phone completely without restoring from a back-up. The problem did not go away.
I'm guessing it is a hardware issue since it affects all the photo taking apps I had. We'll see what the Genius Bar says tomorrow.
Update: Just got back from the Apple Store. The problem was hardware - the front camera was no longer working. This is one of the things I like about an iPhone, the ability to go to the Apple Store to get it fixed. Where would I go to get my Android phone fixed if I had a problem? The carrier most likely. I'm not sure their level of service would be the same.