Yep, Big Brother is here. These chips can be attached to anything, passports, store loyalty cards, clothing, car keys, theater tickets, and are what pets are 'chipped' with. (Though Wisconsin has recently made it illegal for them to be inserted into humans!). One day, the RFIDs on your clothes will tell your washing machine what cycle to use, they say.
But they can be used by supermakets to track stock in transit, maintain store stock control (with automatic re-ordering), and, unlike barcoding, they can hold 'best before' information for stock removal and re-stocking. They could also provide for automatic checkout with no queuing - where the checkout 'reads' the contents of your trolley and presents you with the total to pay. (This means everything would have to be pre-packaged!).
Supermarkets are very keen to know the patterns of customer movement within their stores so as to 'maximise on product placement', i.e.make you buy more. In the past, RFID trolley tracking has been used, but individual item tracking is much superior to this. Should they put salad cream and mayonnaise beside the salads, or have them next to all the other sauces? Tracking will help them make up their minds.
The one instance where I'm fully in favour of RFID is on Singapore's buses and MRT rail transit system. Pay for a top-up card, and tap it on a sensor as you board and again as you alight, and payment is deducted from the card. For uses like this, it's brilliant.