I have no desire to endorse Julian Assange, but that does not mean his claims below are not true or at least partially true:
Facebook in particular is the most appalling spying machine that has ever been invented. Here we have the world’s most comprehensive database about people, their relationships, their names, their addresses, their locations and the communications with each other, their relatives, all sitting within the United States, all accessible to US intelligence. Facebook, Google, Yahoo – all these major US organizations have built-in interfaces for US intelligence. It’s not a matter of serving a subpoena. They have an interface that they have developed for US intelligence to use.
Now, is it the case that Facebook is actually run by US intelligence? No, it’s not like that. It’s simply that US intelligence is able to bring to bear legal and political pressure on them. And it’s costly for them to hand out records one by one, so they have automated the process. Everyone should understand that when they add their friends to Facebook, they are doing free work for United States intelligence agencies in building this database for them.
I would agree with his concerns about Facebook (and Google) and privacy, and would add that it is quite astonishing how quickly people have lumped large quantities of information into the FB database. If an evil dictator was to rise to power now, or in the distant future (yes, computer hard drives have long memories), this source of information would provide a great way to get rid of certain distasteful groups of people.
Regarding Assange’s claims about US intelligence — the truth or falsity of this claim obviously requires solid evidence which presumably is would be rather hard to find.