Google mines behavioral data
For what? Simply to improve their SERP (Search Engine Result Pages). The ultimate aim of Google is to help users to find the information they are looking for (at least it should be their aim). By mining data they have gathered from Google Toolbar, Google Analytics, Feedburner (it is now part of Google) and certainly other free tools, they are certainly trying to get better SERP.
Maybe some of you already thought it was the case. This news is giving a better insight regarding this issue. However, as it is often the case when making conclusions from experiments, their finding is maybe not generalizable to other webpages. This news has thus to be taken with caution. Maybe some of you have an opinion about this? Feel free to comment.