Looks like this will stop (after 24 hours) some companies from doing an initial redirection to set cookies for tracking purposes... Example:
1. Search Google for hockey sticks
2. Click on search result hockeystick.com
3. hockeystick.com issues a 302 to adcompany.com which then issues a 302 back to hockeystick.com
Why the 302? Because in Safari, you could only access cookies in a 3rd party context if you've seen a domain in a 1st party context. Setting a cookie in adcompany.com in a 1st party context gives you the ability to read that cookie in a 3rd party context which could be used for tracking purposes.