Google seems to have released a new button found at the bottom of the SERPs page. The new button is to the right of the normal "search" button but says "search harder". I have not seen this myself, it might be one of those things Google is rolling out to some people. A thread at WebmasterWorld has several people who have seen this.
Basically, if you do a search on a very general keyword, such as cars. It asks you if you want to "search harder", if you click that search harder button, it takes you to a different SERPs page for cars found here. When you click on the link, see the URL: http://www.google.com/search?q=cars&btnmeta%3Dtha%3D1%26seen%3D7d8882011a9da6f0%2CpaQUq1 BgsA8J%2CRVuszxD0ZLYJ%2CKWbRZb06QI8J%2CRsWGZdkk_oUJ%2CEItB 6rHmy6YJ%2C4DBTRhlVuqUJ%2C8pAZTckoaBMJ%2CDk2ynlAPOA0J%2C8uB J_n5AyTYJ%2CXY7ep7ykeoAJ%2C=Search+Harder
Very interesting...As more information comes my way, I will post it.