Karen Goulart
It has helped start revolutions and couriered information in times of disaster. It has let you know what Jaden Smith thinks about trees. Love or loathe the hashtag-happy social network, the great success of the Twitter IPO signals the idea has staying power, whatever staying power means in these days of lightning change. So if CIOs haven't already made it part of their work lives, now would be a good time to start.