There is a use case for, "I wonder what images were taken within 100' of me!"
If the app is on, and tracking photos that were taken, then can resolve it after the fact (and get those photos), I think a lot of people would be interested.
Wouldn't that be in Facebook's territory? i.e., "Hey Facebook, I took these pictures at Bob's wedding. Based on the geotag, can you show me other pictures from nearby at the same time?"
It seems convoluted (not to mention a gigantic drag on your battery life) to do so on each and every device in real-time.
Your phone knows where you were, when. And says, "Here is where I was, what pictures were taken around me?" I want this information regardless of whether I was personally taking pictures.
Keeping a history of where you are can be done without much drain on your battery life. It can just log a location every few minutes.
Is location really the key piece of data differentiating "pictures from Bob's wedding" from "the universe of pictures", though? I would think some concept of tagging that went beyond mere location would be far more useful.
80% of the time (walking down the street, sitting in my office, etc.), I don't care about pictures that were taken around me. For the 1% of the time that I DO care, I can probably easily name the thing that I want to see pictures of. Location is perhaps a handy filter for "tags that might be important to me", but it's hardly the sole determiner, or even a major factor, in whether any given picture will be one that's interesting to me.
And what is the chance that random stranger is using Color? 0.000001%. So why don't you just walk over there and ask him to send you a copy? Social networking at its finest, in real time, at a conference.
If the app is on, and tracking photos that were taken, then can resolve it after the fact (and get those photos), I think a lot of people would be interested.