From what I have read, the camera interface was not complete when Jobs gave his keynote. Since then I have not seen any information regarding it. I guess this is another thing that falls into the wait and see category.
If the pinch were to work for zooming, I assume you would take a picture, then used pinch while previewing the picture to zoom in? You are right, zooming via pinch with one hand while holding the iPhone and taking the picture with the other would be crazy difficult!