I really like this - I think it would be an awesome way for people in cities to leave ephemeral easter eggs with chalk on a brick wall, for instance. Just because a lot of folks don't see the business value or purely technical use doesn't mean it's not awesome.

Or maybe make a meshtag scavenger hunt, with each tag leading to the next clue. Sure, you could do it with a QR code, but these look cooler, are ephemeral by nature, and have more of a fun feel to them.

The image processing code was probably really fun to write, too. Kudos on a really awesome project.