Traditional barcode can only give you numbers, whereas a QR code can give you info like name, email, URL, message, etc... in fact it is a very common thing in Japan. Visit any Japanese site and you will see this thingie. On top of that, most of the handphones in Japan have readers to decode QR code, so in fact it has more usages than barcode.
Actually there is one Japanese freak who writes his/her blog in QR code. Happening huh?