I disagree. First, Google has a decent track record in keeping personal data and advertising separate. For example they claim that their tracking cookie used a

I disagree. First, Google has a decent track record in keeping personal data and advertising separate. For example they claim that their tracking cookie used across the web is not connected in any way to your Google profile. They can make use of a lot of data to show decent ads. Whereas Facebook will obviously make use of all your data because that's all they have. 2. Google makes most of its money by showing ads based on search terms you search for. They also use recent mails in GMail for ads within Gmail. They do not depend on any revenues from Google+. They likely see it as a defensive measure against Facebook which seriously threatens its real revenue model. Their competitive advantage is context, not primarily information about users. Again, for Facebook ads within the social network based on personal information are their sole competitive advantage. It makes more sense to trust Google, at least as far as I am concerned.