Twitter is a micro-blogging service, which limits your entries to 140 characters of unstructured text. It allows you to follow people you like, and to have others follow you. With its 140 character limit, it would not be too far fetched to say that it is the SMS of the internet, with closed user groups thrown in. You could send a tweet, or a mass SMS using the same analogy, to everyone who follows you or you could target your tweets to...