The concept is simple, and is based around the technology known as QR codes. As an American, I was only marginally aware of what these things were, having seen them on packing slips and such in the past, but I've seen them discussed here and there before. Essentially, what they are, I've found out, is a barcode like system that encodes everything (numbers, alphanumeric characters and even binary data) into this little box-like code. It's designed so that you can take a quick snapshot with the grade camera that typically comes on a mobile phone.
Simple, but interesting, and in Japan and parts of Europe, maybe even useful. I don't think the QR code craze has hit America quite as hard as it has hit there (and Stan, our European editor tells me that where he is, it isn't a thing of familiarity for the culture), but it easily could, it looks like, as the mobile software to interpret the codes are freely available.