How Facebook Envisions the Future of Our eLives And Why It's Not a Good Idea
plus.google.com
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The same information that a governmental agency would need a warrant to acquire the same information that people give up to social networks or other websites in general without a second thought
And FB is a single-source for that warrant who likely has more informal processes for satisfying some requests without warrants. This is why the Carlyle Group (CIA) invested in Friendster (and probably FB too).