I agree with this article:
as there are obvious dangers of posting your entire life online. However, I would stay away for an entirely more mundande reason; most of it is just utter junk. Imagine a scanrio where the world falls back in to the dark ages and nobody could rescue the twitter, facebook servers etc. What would we lose? Probably nothing much; it would have the polar opposite effect to the destruction/ loss of the Library of Alexandria. How important can hundreds of millions of bits of text saying “just got back from the pub” be?