As I understand it, traditional search engines already use the feedback of which links people click on (I think they used to mangle the links in order to be abl

As I understand it, traditional search engines already use the feedback of which links people click on (I think they used to mangle the links in order to be able to track this, but it seems that at least Google has now switched to some JavaScript trick.) If the goal is just to improve search quality (and this may not be the case, I'm not sure), then whether you'd reach that goal will hinge on whether you can get more accurate information by letting people vote explicitly, and after they have already seen the page, rather than implicitly, and after they have only seen a short summary.