http://www.theconservativevoice.com/articles/article.html?id=11537
Fortunately they have an option to opt out, though no one ever heard of it. Jeez. What are the internet companies upto! And add to it, they track by machine, not by user id. So you need to opt out every single computer you use. Whoa?!
http://privacy.yahoo.com/privacy/us/beacons/details.html
!