Rise and Resurrection of the 2D Barcode?

2D barcodes for mobile use have been on the horizon for at least half a decade. My first blog entry on the topic I could find with a quick search seems to be from 2006 and I have pretty much given up on the idea seeing a breakthrough anytime soon just this year. And just when I've put the idea out of my mind, they seem to be resurfacing quite massively. A case in point is the picutre on the left which I have recently taken in Cologne. They can't get any bigger than this, can they!? When looking a bit around in that neighborhood I noticed a few more 2D barcodes on a billboards and also restaurants (with links to their Facebook account or website). Looks like the advertisement industry keeps pushing.