A short deviation from art for a moment…
In short, if you have a Google account such as a Blogspot blog like mine, or a Youtube account, then virtually everything you do whilst signed in to your account (and most of us are likely signed in automatically) will be tracked and logged by Google so that they can influence your search results and deliver targeted advertising to you.
It doesn’t seem like much of a problem on the face of it, but it is a significant change in policy. I’m among those who don’t see this sort of thing as a benefit. It already frustrates me that Google search results are tailored based on search history.
If such things concern you, then you can go to http://www.google.com/history and see some of the information Google has on you. You can remove all history while you’re there and this will, in theory, also “pause” history tracking for all but your Google searches.
If you are deeply concerned about your privacy, you could close down your Google account but this will, of course, delete your Blogspot blog and Youtube account completely.