That USA Today article is a little deceptive when it says: "With its "like" buttons on websites across the Web, Facebook has been able to keep tabs on what its 1.3 billion users are doing." The fact is that unless you block Facebook on your computer, then every page where there is a Facebook like button (most do) will drop you a cookie which is for tracking. Yes, it doesn't put your name beside it unless you're a Facebook member, but it does attach to your IP. Facebook tracks everybody.
I chose not to, but I don't blame somebody for using Facebook since it does provide a valuable service. However, whether you do or not, it is a good idea to be proactive and aggressive in cutting down on all the tracking. Everybody is doing it, not just Google and Facebook. One thing that people forget about is that clearing your cookies does not do so much any more. Local shared objects (LSOs) are commonly called "Flash cookies" (Google it), and they are essentially everlasting unless you figure them out. They are hidden deep in your computer and duplicated in two separate places. Even if you delete both of those directories, and all the ones leading to them, they still come back! I finally solved the problem by deleting them, and then immediately making the topmost directory (and thus all the ones below that) unreadable and unwritable - even by me.
You really have to go to extremes to keep your information from being collected by others. It is not just a matter of what you put out there. It is a matter of what those out there take.