This also has me thinking about the "Light Field" story from two days ago. ( http://www.hackerne.ws/item?id=2681554 ) If that technology becomes common, and camera resolutions continue to improve, I bet you could lift people's thumbprints from photos of them waving on Flickr. That sucks if you use a biometric thumb lock like they do in the shared office space I work out of.
Your thumbprint is like a password which you can never change. If your thumbprint appears in a single photo of you ever, there's no locksmith that can help you get that JPEG back from Lulzsec! :-)
But how do you not show something online? If it can be seen, it can be photographed. If it can be photographed, anyone can put it online.