Google Product Search is becoming a pay-to-play service called Google Shopping. In addition to potentially reshaping the way online marketing of products works, the move is part of a major policy transition by the technology giant.

Previously, Google's official position had been against requiring manufacturers of products to pay in order to get placement in search results. Now, the company is saying the new policy will help consumers, because it will relay more accurate pricing.

'Purely Commercial Model'

Currently, users can search for products through Google Product Search by entering the product name into the search field at and clicking "shopping" on the left. The results are derived from data feeds about products at participating stores, via a free tool that Google provides. Searchers can then choose to filter the results, such as by price.

The transition to Google Shopping, which was announced Thursday on the official Google Commerce blog, is expected by the fall. On the blog, Product Management Vice President Sameer Samat wrote that the move to "a purely commercial model" will encourage merchants to keep "their product information fresh and up to date," which will translate into better shopping results for users and higher quality traffic for merchants.

Merchants will also receive incentives to participate, such as a monthly credit of 10 percent of total Product Listing Ad spending through the end of this year, or a $100 AdWords credit toward Product Listing Ads for existing Google Product Search merchants.

Ranking in Google Shopping will be based on a combination of relevance and bid price, which Google said was comparable to Product Listing Ads currently. Eventually, there will also be opportunities to market special offers.

Trusted Stores Program

There will also be an option for merchants to participate in the new Google Trusted Stores program. E-commerce sites in that program will offer background on the merchants, such as ratings for on-time shipping and customer service. Google will back up merchants who have been certified as Trusted Stores, with a $1,000 lifetime purchase protection guarantee for each shopper.

The change in Google's policy centers on its long-time insistence that it doesn't offer better "organic" search results as a result of a financial relationship with a given company, which is called "paid inclusion." In fact, Google cited this purity of their editorial search results in its initial public offering information and other communications.

Some observers have noted that Google Hotel Finder and Google Flight Search, both launched in 2011, already offer better search results to companies with a financial relationship with Google -- especially in comparison ads that accompany these results, which are marked by subtle indicators to show sponsorship is involved.

In those instances as well, Google has said that the paid listings allow it to present more accurate information.