I received the following message about Yahoo's use of "web beacons" on a Yahoo! Group I'm subscribed to. Regardless of whether or not you are subscribed to any Yahoo! Groups, if you care about your privacy, you might want to opt out of this. Note that you have to opt out on every browser you use.
Yahoo is now using something called "Web Beacons" to track Yahoo Group users around the net and see what you're doing and where you are going - similar to cookies. Take a look at their updated privacy statement:
About half-way down the page, in the section "Outside the Yahoo! Network", you'll see a little "click here" link that will let you "opt-out" of their new method of snooping. I strongly recommend that you do this.
Once you have clicked that link, you are opted out. Notice the "Success" message the top the next page.
Be careful because on that page there is a "Cancel Opt-out" button that, if clicked, will *undo* the opt-out. Feel free to forward this to other groups.