Twitter's link service, t.co, is designed to make shortened links easier to read and safer to follow. Initial tests have gone well, too. But an announcement that Twitter will start tracking every t.co link users click has caused a bit of a stir. Twitter sent an email to users last night that in part stated, "In the coming weeks, we will be expanding the roll-out of our link wrapping service t.co , which wraps links in Tweets with a new, simplified link. . . .