I've been a huge fan of qr codes for ages now (no shit I hear you say, having taken a look down the page).
Being a direct marketing guy by trade I think this technology could be to the physical world what the link is to the internet. Its the notion of digital touching (and hopefully enhancing) the real world that tantalises. Whats also interesting is that response to codes is getting bigger and better by the day. I'm astounded that already QR codes can exceed SMS response when used in a direct response context.
So QR codes are a great direct response tool, they clearly make a promise of value 'on the other side'. And as the mobile internet continues to grow and get faster the experience will only increase in value. Plus, no more conversations about making the 0800 number or URL bigger in the ad.
These things stand put like the proverbial dogs bollocks (much to the chagrin of some Creative Directors).
In my day job I just posted some results from some of our QR campaigns - check them out if you're interested.

Simon Morgan is a Partner at Myne a specialist marketing consultancy owned by Publicis Mojo Australia.
This is his personal weblog and of course doesn't necessarily reflect the views of his employer, although he suspects that they would probably agree with most things said here.