How to Make a Search Based on Google's Product Search
You may have seen the Google Product Search and may have thought that it would be useful to include a customized version of the search into a website or application. Unfortunately, you can't just create a custom search engine based on the Product Search using Google's custom search creator.
So, how would you incorporate the Product Search into an application? The answer is to use the Google Base API. The API allows for you to call a feed and if you use the [item type:products] option it will use the Product Search data.
The API allows you to receive the feed in Atom, RSS and JSON formats. Google has also made it very easy by making a feed URL builder (you can access the builder here).
So, if you want to make an application using the Products Search now you can.