I also agree with mattc (like most tech enthusiasts, I have a strong luddite streak): By all means use a camera (safely - I've no objection to ride-by photos taken from the back of a tandem, for example) as way to make notes for yourself in preference to writing things down in a rush at the roadside, especially if you're dyslexic and liable to transpose numbers, or your camera is more waterproof than your brevet card. You can copy the details onto the card while digesting CAKE at the next control.
Cameras can also come in handy as a controller-friendly[1] means of obtaining some form of proof when things go wrong. I've taken timestamped and geotagged photos of myself standing in the dark outside a unexpectedly closed commercial control, and of a group of cyclists looking confused at a recently-nicked signpost, to good effect.
But I don't see much point in going to the effort to use photos routinely as electronic PoP; you might as well use GPS.
[1] They may accept you showing them a photo on a smartphone screen, but wouldn't know what to do with a GPX file.
