This is a feature in that "gee, I wish I'd of thought of that" category. The latest update to the TomTom app (version 1.5) lets you select any photo that has been geo-tagged and navigate to that location. It's great for finding that favorite picnic spot, or that great photo location.
I tried the feature out today, navigating to 2 locations I had in my iPhone photo roll. In each case, the app showed a map of the location, and with a couple of clicks I was on my way.
The app also now supports the iPhone 4 Retina display and the speed of the app is supposed to be faster but I didn't see anything dramatic. TomTom U.S.A and U.S. & Canada apps are currently available for $49.99 and $59.99, respectively. It's a really full featured way to navigate. Navigating to a photo is a really great idea, and I'd like to see some of the other nav apps add this feature as well.
The only thing I don't like about the app is there is no clear way to turn it off. If you want to interrupt your trip, you can bail out of the app but it keeps running in the background. If you want it to truly stop, you have to close it in the multi-tasking GUI. That criticism aside, TomTom is a worthy addition to your iPhone, clearly in the top ranks of nav apps that will get you where you want to go, and with this new release, TomTom can get you there in a pretty innovative way. Check the gallery out for some screen shots.