Think Information. Think Security.
Facebook, Inc. = FBI = Federal Bureau of Investigation.

Whether this equation is true or not, the popularity of facebook among its users will always out weight any similar claims.

WikiLeaks editor-in-chief Julian Assange has branded Facebook an “appalling spying machine”.

According to Assange, whose WikiLeaks whistle-blowing site has propelled him into the media limelight, US intelligence services have direct access to records of Facebook users.

From Wikipedia:
Social engineering is the art of manipulating people into performing actions or divulging confidential information, rather than by breaking in or using technical cracking techniques.[1] 

While similar to a confidence trick or simple fraud, the term typically applies to trickery or deception for the purpose of information gathering, fraud, or computer system access; in most cases the attacker never comes face-to-face with the victim.

"Social engineering" as an act of psychological manipulation was popularized by hacker-turned-consultant Kevin Mitnick. The term had previously been associated with the social sciences, but its usage has caught on among computer professionals.