Originally called Froogle, it's always been free to use, and has been a great way of companies getting traffic from people searching for the products they buy.
That's all changing though- starting in the US about now, Google Product Search is getting a new name, Google Shopping, and a new business model where only merchants that pay will be listed. It’s the first time Google will decommission a search product that previously listed companies for free. The company says the change will improve the searcher experience, but it will also likely raise new worries that Google may further cut free listings elsewhere.
Is this a purely mercenary move that will see independent stores wither under the advertising might of the big retailers? Or a move, as Google says 'to deliver the best answers for people searching for products and helping connect merchants with the right customers' ..... but weren't they trying to do that anyway?
See some great comment here: Search Engine Land