the local super market are giving these devices to customers while walking around shopping. you scan your club card when you walk in the door, so they know who you are, and then assign one of these to you. you walk around the super market, picking up items, and scan them and place them in your basket or trolly. then at the end of the shopping spree, they scan a little barcode on the cash register, and your club card, and all the data is uploaded so they know what you bought. you then pay and your finished! takes all the pain out of shopping! Very cool reason to go shopping!
Here is an other shot of the device: