In the fight for share in the social media space, and in the fight to produce something of actual value from the big data stores being collected by these large internet firms, the push to string linked user data together to provide interesting information to online friends causes queasiness among users who have grown used to a de facto privacy that developed back when companies were pretty poor at exploiting the massive data files they owned.

One example cited by the Wall Street Journal was the Navy petty officer who signed up for a Google photo storage service (requiring Google+ membership) discovered that he unknowingly had set off a chain of links that caused his name to be linked to a software review he'd written elsewhere.

Coupled with different, ever-changing and fairly opaque sharing policies, the social networks are finding themselves often at pains on one hand to apologize to users for over-sharing; yet also they find themselves in a desperate competition to be the best at creating applications for sharing.

These perceptions of privacy invasion affect to a great extent the political momentum behind regulatory and legislative efforts to curb online advertisers' capacity to use similar forms of data.