John Battelle has posted a review of Amazon’s new search engine a9.com. He indicates that it is built on top of Google. There is one slight difference. There is a “Sign In” option, and after performing a search, the line ” Hello, sign in to enable site features.” appears at the upper right corner. When you click “Sign In”, you are asked to sign in to your Amazon account. After that you are able to view your search history, starting with the last 24 hours. It also lists the books that match your search.