Instructions for Safari
While we don't yet have a Safari version of the Google advertising cookie opt-out plugin, Safari is set by default to block all third-party cookies. If you have not changed those settings, this option effectively accomplishes the same thing as setting the opt-out cookie. To confirm that Safari is set up to block third-party cookies, do the following:
From Safari, select "Safari" in the menu bar, and then select "Preferences"
In the Preferences Dialog Box, select the "Security" tab
Make sure the "Accept cookies:" setting is set to "Only from sites you navigate to". You can also set this option to "Never", but this will prevent many web sites that rely on cookies from working.