Marketingshift noted that Google Base results have been mixed in with Organic search results for certain types of search queries about cars.

"Yesterday a stir broke out about the AdSense bot adding the content of sites in the AdSense network directly to the Google search index and thus having higher rankings due to fresher content on those sites… which is the first legitimate claim I’ve heard from anyone that Google has started to tamper with their results. Then today I’m greeted with a car search refinement tool (which is obviously geared at selling cars from Google Base - just look at all the listings from Cars.com in this screenshot). It’s quite clear Google is bending to Wall Street and doing whatever they can to generate more revenue but it also appears they may have started cutting corners.

I’m not sure if the car search refinement tool will be on all car results or if they’re just testing things for the time being but it’s annoying and I’d like the real Google to stand up please."

I was able to replicate the results but I don’t see any problem with adding customized Google Base searches.  On a related note here’s something I found out about from WebmasterWorld this week.

Google is using a new crawl technology to fetch information from any source, including AdWords. If the same page is in Google’s BigDaddy Cache already (because of a previous fetch of the page) it’s going to use that page.

In a way, Google is just building the equivlent of of the kind of caching networks that have been in place on Wall Street for over 10 years (I know because I used to work on some of these networks). It was long belived that if you can cache content - you can cut down on bandwidth and decrease response time.