The Amazon iPhone App (doesn’t work on anything but iPhone 3GS or 4) got a little update today that will let users scan barcodes and instantly compare prices at Amazon.  For instance, you are at a store buying a lamp and want to see if Amazon has a better price, you’d point your iPhone at the barcode and a few seconds later (literally takes 2 seconds) you’d see the Amazon price with the option to buy.  Bam!