Google recently announced that their Google Shopping feeds will no longer offer up product details in search results for free. The original program, started about 5 years ago, let manufacturers, retailers, and distributors load specific product information into Google's search system. Product detail results would show up within the main search itself or within the specialty shopping tab http://www.google.com/shopping.
The original system (called Froogle) started off gathering information by crawling existing ecommerce sites, but Google eventually decided that allowing vendors to upload their own data would make it easier for everyone. Microsoft soon followed with their own version for MSN/Bing.
Neither service charged for product listings, allowing them to crush pay-per-click price comparison sites like shopzilla, pricegrabber, nextag, bizrate, etc. But now Google has decided to switch to the very same pay-per-click model it was competing against only a short while ago.