So I had heard a bit about Munzee its a lot like geocaching except you find a QR code you scan with your smart phone instead of a cache. Many people have been placing them on geocache containers. The one I found yesterday was hidden by Kelly in front of his work. Its the first one in Grants Pass.
While cell phone coverage has been growing there are still out of the way places that a Munzee just wouldn't be possible but a cache would. I can see them being much more successful in an urban environment.
I might put out one of my own and I'll probably scan them when I see one. As for seeking them out... probably not, but then again I don't even go geocaching much anymore.