Twitter (http://twitter.com) is a free networking and micro-blogging service that allows its users to send and read other users' updates, called "tweets." This business model continues to be criticized for not being viable in the long-term. Spend some time studying how Twitter does business. How does the company earn money? Does it or does it not have a business model with long-term potential? If it does not have a viable long-term business model in your view, what changes to its business model should Twitter make to increase its competitiveness?