Generally speaking
This means they indexed every hipper-than-thou's tweets about what was for lunch, what they were doing, etc. A lot of chaff in there. Anything really important, I'm sure was saved by the sender or the receiver, I'd hope. Nothing earth-shaking that could be packed in 140 characters that I've heard about has come out Twitter. Anything relatively important has been quoted to death in news stories and indexed already by the news site or Google. So I wonder what's the point?