As much as twitter seems to be the latest fad the kids are playing with, I do find it makes me think. Ok, not to the extent a Rubik cube or a crossword puzzle would, but in its own sort of way it exercises my mind.
I find myself quite often typing something into twitter and going over the 140 character limit. I think have to work out how to re-word what I said, cutting down the length of what I type but still making sense. Ok, quite often I end up with something akin to Newspeak from George Orwells book 1984, but often I find that there is actually a far more effective way of saying something using less words.
Of course some people end up replacing “to be” with “2b”, but that aside it at lease makes you think about what you are typing, even if you do end up butchering it afterward.