So I had to check it out. You should too! Heres a link.
Basically all you have to do (unless you are more savy, so far I have done the minimum) is set up a spreadsheet in Excell to create your "Data Feed". Save this spread sheet as a .txt file and go about setting up your Google Product account (be sure to put your website in the setting, the data feed won't work without this)
The help info was great and I've got my first feed running.
Here is the info plucked right from their site to explain how it works to your advantage to do this (did I mention its FREE - so why not! - common, go make a spreadsheet!)
Increase traffic to your store with Google Product Search – for free
Google Product Search helps shoppers find and buy products across the web. As a seller, you can submit your products to Google Product Search, allowing shoppers to quickly and easily find your site.Increase traffic and sales
Product Search connects your products to the shoppers searching for them, helping you drive traffic and sales to your store. Your products will appear on Google Product Search and may even be displayed on Google.com, depending on your items' relevance.Submit products for free
Inclusion of your products is completely free. There are no charges for uploading your items or the additional traffic you receive.Reach qualified shoppers
Reach shoppers precisely when they are searching for items to buy on Google.