Personally I think they would take off if we had some sort of large plastic dedicated device that plugged into your computer to scan these things. Perhaps shaped like a cat; people like cats.

For anyone wondering what jlgreco is referring to, it's the CueCat:

http://en.wikipedia.org/wiki/CueCat

I still have one in my junk electronics box in the basement. It's what I always think of with QR codes.

Ridiculous.

Doesn't it seem idiotic to duplicate what we already have? (English characters) in some arcane non human readable, punch-card-esque idiocy?

In a few years, all cellphones will be able to read english characters and words. There will be no need for QR punch-cards.

Imagination. moe's got it. If as Brin suggests, Glass is available next year then scanning QR codes is one of the brain dead obvious launch apps for it. QR codes will be less variable and more reliable (under arbitrary conditions) than OCR at that point as well as being able to hold more information per square inch. They will be quickly translatable and displayed as human readable information floating in front of your face - with little to no effort required on your part.

The information density of QR codes is much higher.

In a few years many people will also be walking around with AR-glasses (e.g. google glasses) which may very well scan the codes automatically and overlay them in the viewport with whatever they want to represent.

Maybe using something like NFC? so you come near to a poster and it pushes a URL or something to you?

Or a 'smart billboard' perhaps: http://mashable.com/2011/04/16/smart-billboard/