QR codes have yet to conquer the US and Europe but are prevalent in mobile phone-crazy Japan. Denso Wave, a Tokyo-based tech company, invented the nifty little two-dimensional bar codes as early as 1994. And they are everywhere now in Nippon: magazines and newspapers, billboards, clothes, beer cans, maps, business cards, cigarette boxes etc. etc. Scanning the QR code you see above should lead you to http://www.crunchgear.com, for example.
And the Japanese now even use QR codes on graves, as shown in the video below. It may sound macabre at first but seems to be a way to let people close to the person in question interact with each other without hassles, i.e. in the form of a mini social network that you can access with your mobile phone.