Twitter has over 200 million registered users and at the Mobile World Congress today CEO Dick Costolo announced that “40% of all tweets come from mobile devices. 50% of all Twitter users are involved with more than one platform… Twitter should be like water. It’s immediately available and instantly useful”. Costello also said that 130 million tweets are sent per day and increasing at a “ridiculous rate”. Those numbers calculate that 65 million tweets are made from a mobile device. No word on which platform is the most popular but we’re guessing it’s iOS.