Google has released Google Shopper for iPhone, which was previously only available for Android devices. Google Shopper is an app that provides information on products that you may wish to buy and lets you read product reviews and compare prices at online and local stores, using location services.
You can search for a product using text input, Voice Search or by scanning the barcode with the iPhone camera. Once you have found the product you want, you can then find the item at nearby retailers and with some stores you can even check if they have it in stock. You can also build gift lists and star products for future purchase as well as share items with friends across your social network.