Google created the relationship when they enabled user tracking features in IE and Bing Toolbar, then used a specially created Google page as the HTTP REFERER to the desired page. Go ahead and duplicate the experiment using a non-Google page or file. I'll bet Bing "steals" those results, too. Google seeded Bing, plain and simple.
Note also that the example search links in the blog post are all from the non-SSL Google search. User tracking doesn't necessarily rely on the HTTP REFERER in this case, since the browser already has access to all of the necessary information. But it would still be interesting to see the experiment repeated using the SSL-encrypted Google search, which disables referrer information, along with non-Google sources.
Note also that the example search links in the blog post are all from the non-SSL Google search. User tracking doesn't necessarily rely on the HTTP REFERER in this case, since the browser already has access to all of the necessary information. But it would still be interesting to see the experiment repeated using the SSL-encrypted Google search, which disables referrer information, along with non-Google sources.