[ryusage]

It seems pretty clear from the way they talk about it that they're tracking who sees each ad on each bin in exactly the same way google tracks who sees each ad on each web page. The obvious next step for such a technology is to show specific ads only when people who might care about them are nearby. It's pretty genius really - it would put them miles ahead of other physical ad companies, at least until the rest started doing it too.

But yes, the obvious downside is that instead of worrying about google knowing everywhere you go on the internet, you now have companies that know everywhere you go physically as well.