[JoshTriplett]

As a tag system, this doesn't seem to have any advantages compared to QR codes, and it has several disadvantages (central authority, possible conflict, only encodes the key rather than the direct value).

However, this system does have an advantage for other purposes: those where the ability to reproduce it from memory is important. QR codes aren't memorizable; meshtags seem more so. Consider how many people prefer Android swipe-unlock patterns rather than PINs or passwords. Many people have good spatial memories, much more so than their memory for arbitrary strings. You could use this in cases where the property of being able to reproduce this from memory is important. Figure out how many bits of entropy this can represent, create and document a perfect 1:1 mapping between meshtags and an encoding, and target use cases QR codes can't handle.

For that matter, how robust is this against minor errors, and how high-resolution can you make it and still reliably resolve it? Can you pack this more densely than a QR code and still reliably read it? If so, you've got something particularly interesting.