Facebook revenue (2009): ~$650m

Twitter revenue (2009): ~$4m

Twitter just don't seem to have a business model. They're making a paltry handful of cash from sponsored tweets and a slightly larger handful from the Bing deal. Beyond that, they don't seem to have much of a plan. I don't see how you can effectively monetise a platform like Twitter. It smacks of bad old bubble era thinking. Great protocol, great community, great service, lousy business.