Jaime from Google reminds us in a Google Web Search Help thread about a 1.5 month old search option feature Google added, named "More shopping sites." Basically, if you conduct a search on Google, click on "search options" and then click on "More shopping sites" Google will try to show you results from sites selling things.
Here is a picture:
This kind of reminds me of Yahoo Mindset, a tool Yahoo created a while back allowing people to change the type of search results from shopping to research with a slider. Here is an old picture of the slider:
Now, personally, I'll probably stick with using Google to research products and then once I find the sku, use both Google, specialized shopping search engines and Bing Cashback to find the best deal.
Forum discussion at Google Web Search Help.