It's that last capability, taking photos, that makes QR codes so important. If you download one of the many free QR reader such as this one from Kaywa and see a QR code, just open the reader, take a quick snapshot of the code, tap on the photo, and your phone's browser is redirected to the encoded location. Here, for example, is the first QR code I ever created. Scan it with your phone, and you'll be taken to my Amazon page where all my books are for sale.
How many consumers scan these codes? I don't know yet, but the technology is free and easy, so it's going to be fun to find out. I suspect that over time, QR codes will be a real boon to us self-publishers and do-it-yourself marketers.
Have you tried using them, either as a seller or as a consumer?