Who hasn’t heard about the censorship supported by tech companies from that democratic, freely-speaking, world model southern neighbour of ours? Google, Yahoo and Microsoft each deliver different search results inside China than elsewhere. Reporters without Borders reports that Yahoo! is the worst current offender.
Their test results, conducted on several engines both in and outside China, show a definite tilt towards displaying ‘authorized’ sources inside China. Chinese search engines appear to control information by not indexing certain content and by preventing users from getting results which do exist.
Politics, policy and placement come together in search engines. In addition to the report mentioned above, investigate the impact yourself at the google vs google site. As the site cautions, this is an experiment which might disappear.
Global free speech might be a bit heavy to ponder. The same site offers a google to yahoo comparison. By graphically displaying the relative positioning of search results, one can literally see the tilt of one engine over the other. Very handy for checking how these two major search starting points treat items of interest to you.