Someone responded to my ZDNet comment with a summary of the advantage of indirect mobile tagging which I think is relevant to point out:
The big advantage of indirect tags like this is that you can update where they point/what you get without having to reprint the posters etc. It also allows for a certain amount of screening to make it harder for them to be used for phishing, porn, etc. And it allows the tag owner to collect statistics on how the tag element of their marketing campaign is going.”
Nevertheless, I still don’t think that I’ll be using my phone to read Microsoft’s tags if it means sending information about myself, my phone or my location to their server, but that’s just me.