In the book I talk about digital products that do no information processing of their own. For instance, an electronic subway card does not actually do any computation, but is still a digital product since it allows you to interact with a digital payment database.
An easy way to identify products has been to use visual codes, such as the classic barcodes that you see in supermarket checkout counters. However, I argue that barcodes have many disadvantages, and for many tasks they are not really necessary! Image recognition technologies are becoming so good, they can identify objects without any specific codes.
Case in point: Toshiba has developed a supermarket checkout counter that identifies fruits by sight - no barcode needed! While this is still an early system, it points the way to a near future when every object around us will be recognizable and potentially part of a digital system.