About half-way down the page, in the section on cookies you will see a link that says 'web beacons'. Click on the phrase 'web beacons'. ( http://privacy.yahoo.com/privacy/us/beacons/details.html)
That will bring you to a paragraph entitled "Outside the Yahoo Network."
In this section you'll see a little "click here to opt out" link that will let you "opt-out" of their new method of snooping. ( http://pclick.yahoo.com/p?optout)
Once you have clicked that link, you are opted out. Notice the "Success" message on the top of the next page.
Be careful because on that page there is a "Cancel Opt-out" button that, if clicked, will *undo** the opt-out.
This applies only to a specific broswer, rather than user, so you have to do it for each browser/computer you use.
Pass the message on!