I think these are just RFID tags, I think they are the same thing the put into pets so if they go missing they can look up their owners etc...
sooner or later they will be in everything and you wont have to manually scan things as you check out you will just walk under a scanner and it will scan all the items in your cart and charge your card...
smart pass or whatever it is from exxon mobil is an RFID chip is im not mistaken