.... and they got a TON of press worth millions.
.... and the word of mouth has been staggering.
.... and they could do this every week for a year and still not lose as much money as was invested in the CueCate.
Move on peoples.... nothing to see here but common sense.
A quick glance at Wikipedia shows that the QR spec was laid down long before CueCat even existed, and the initial technology was based on parts tracking in industry, not consumer usage.
It should also be pointed out that still nobody uses general-purpose QR codes. As a boarding pass? Sure. As a concert ticket? Sure. But when's the last time someone eagerly whipped out their phone to scan a QR code in a magazine ad?
But as you say, it likely has little to do with the CueCat.
Even John Gruber has been positive on the promotion: http://daringfireball.net/linked/2011/05/28/gaga-amazon