We use the information we collect from all of our services to provide, maintain, protect and improve them, to develop new ones, and to protect Google and our users. We also use this information to offer you tailored content – like giving you more relevant search results and ads.
The new policy allows Google, for the first time ever, to freely share information between its various sites so it can create a more accurate model of users' interests and, thus, target ads more accurately. Short of deleting your Google account, there is no way to opt out of the forthcoming privacy changes.
Many users would rather give up a bit more privacy than give up Google. How about you?