It does a web search on the UPC code, and in most situations the results contain an online store where the book can be purchased. If you have Google Shopper installed on your Android device, it can also use that to display information about the product as well.

This would benefit a user who would use their eDGe to store their shopping lists. At the store they could scan in the barcode to see more about a product, compare similar products, and compare prices. Google Shopper also has reviews. Although the online abilities will be rather limited unless you are in a Wifi-enabled store/mall, or have the 3G model of the eDGe(which is yet to be released). Although the barcodes can be stored on the device and then looked up once a connection is found.