Apple has recently filed patents for a "folded lens system" (via AppleInsider). The patents describe a complex system of lens elements and prisms to redirect light into the sensor, which would sit below. The patent also mentions a full-frame equivalent focal length of 80-200mm. Why is this important?
Camera lenses with longer focal lengths can better capture details from far-away objects. But in order to achieve a longer focal length, the lens generally needs to grow longer physically as well. This is bad for anyone who doesn't want a huge camera bump on their smartphone. But if the technology in Apple's new patent can be put to use, future iPhones could offer powerful telephoto lenses, without the camera bump.
Of course, this is all speculation for now, as the patent doesn't guarantee that a new feature will arrive on the next iPhone. But if it does, this could easily be one of the coolest innovations in smartphone photography.