See my delicious tags for reference to article: http://del.icio.us/andyramsden/qrcode
This article introduces a very interesting application of QR codes through class assessment and feedback. They piloted the use of QR codes in a similar way to many UK HEIs using personal response systems. An interesting difference is that the student could also quickly link to a discussion board for further in class feedback. The lecture would then do as they will with this information.
It would be very interesting to see how difficult it would be to hock in a survey / polling tool. One for the technical team :-)
Another test worth carrying out would be to see just how easy it is to present a number of choices on one projected slide. The study used handouts, however this would not scale for large group undergraduate teacher in the UK.
The final observation thinking about implementation is that not only would we have to encourage the use of phones, but also provide wireless networks in the lecture spaces so that students can engage with the use of QR code feedback without having to pay.