"Trying to kill" would have been more apt I suppose. They're pouring tons of money into getting placements in women's mags. Which would also explain why most of us haven't yet seen one.
The biggest issue I see with the Microsoft tags is that the colours are blindingly annoying. For some reason my eyes try to blend the colours together and it gives me a headache. I don't have any such problems with QR Codes.
I've never seen a Microsoft tag in the wild either. I've seen QR codes in almost a dozen places. Most of those were a Google Places link, but a local history museum uses them for links to an audio tour at each exhibit.