Given the success of Google it was inevitable that other companies are trying to take some of their market share. As well as the inevitable (Microsoft and the other search engines) others are trying to leverage their market share in other areas into search and this explains the big move by Amazon who have launched their a9 search engine. They have added extra fetaures being able to save your searches and being able to see comments from other visitors (in a simialr way you can read comments on the various products they stock) as well as the obvious, like integrating it with their product searches.
One major concern is that they already hold your real name, address and credit card details. As with concerns about other dedicated servcies branching out into other areas (like Google moving into Gmail) there are concerns about these firms being able to gather a vast amount of information about you (clearly it would destroy their business if they were caught using it but who knows when a government agency can get a warrant for your records?). So possibly not something for the paranoid
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