1. Providing users with more intuitive functionality across Google properties (Search, Gmail, YouTube, etc.), and
2. Providing advertisers with more relevant targeting options across Google properties.
The key distinction here is “across Google properties.”
Google will be able to provide advertisers with a richer picture of their users for advertisers to target with remarketing, interest category targeting, and demographic targeting. (Users can see how Google defines their individual interest & demographic buckets in their Ads Preference Manager.)
As an example use-case, let’s say someone visits your website on their mobile phone and adds something to their shopping cart. They abandon their cart and leave your site, but not before you add them to a remarketing list you’re building within AdWords. Assuming the user is logged into their Google profile, you’d be able to target them with your remarketing ads when they’re browsing the web at home from their iPad later that night. Furthermore, you may find that users interested in certain topics are more responsive to your remarketing ads. Google’s new policy will enable them to boost the accuracy of the interest category inferences for their users.
Expect to see more Google advertiser tools rolled out over the next few quarters that make use of the cross-property and cross-device advertising functionality promised by this policy.