It shouldn't be too difficult to do: 1) an inexpensive, plastic lens that I snap onto my cellphone (lens helps camera focus on barcode even when barcode is two inches from lens), the snap-on-lens including a "distance-holder" that keeps the scanned product-barcode straight and in focus, so that a clear image is scanned by the camera and delivered to... 2)...a java applet in my cellphone, that decodes the image into a barcode and sends it via SMS to... 3) ...a mobile service provider that returns useful information about the product I scanned

"....Hate to point it out, Edna, but you better leave your hands off that jar of peanut butter. The crazed scientists at ACME Corp are trying to introduce a new genetically altered mutant peanut from Mars... Greetings from Greenpeace.org"

Or some such thing.