Microsoft Word used to have a summarization engine. You could specify a maximum length, and it would remove sentences, in a surprisingly intelligent way, to get to that length. Twitter readers now need such a feature. Just because someone sends huge tweets doesn't mean they have to be displayed.
I think it's very risky to do something like that with someone else's words without consulting them. Imagine a satirical tweet with exactly the wrong "unnecessary" sentence removed. Suddenly your life is ruined because you said something that makes people angry.
Not as nice as being able to write the summary yourself, but certainly an interesting single-player game.