There are basically two ways a product can show up on a Google Product Search–either under its own individual listing with other similar products, or grouped together with other identical products. Examples of each can be seen below:
For general products that may not be sold by many other merchants, consumers will get the former page and are presented with an assortment of similar options for what they want to buy.
However for specific products that are sold by other merchants, Google will group merchants selling identical products together as seen in the latter image. This provides consumers a better experience who already know what they want in choosing which merchant they want to purchase from.
While currently not required, it is highly preferable to be listed within the product pages if one exists, as consumers will more likely click on these product pages rather than individual listings.
However Google is going to soon change that:
Starting in late August, product offers in the Electronics, Books, and Media categories from US merchants may not appear in Product Search if your data feed does not include the necessary unique product identifiers, such as MPN, Brand, GTIN/UPC/EAN or ISBN.
So merchants in these categories who don’t provide unique product identifiers above will risk not having their products show up on a search anymore.
Merchants who sell within these categories should already be able to get this information from their supplier, but to double check, each product page on Google will have the unique product identifiers listed on them:
For example: http://www.google.com/products/catalog?q=2gb+sd+card&hl=en&cid=16624230746745864635&ei=DLU7TL-VIIv62ATk0KDvDQ&sa=title&ved=0CBcQ8wIwATgA&os=tech-specs
Ideally once Google rolls out this feature, within their Merchant Center login there will be details on which products are matched up vs which don’t, along with possible recommendations/suggestions on what they’ll be listed under.