The problem with this assumption of early virality being important is that the value of this property drops significantly over time. There is a critical inflection point where this pseudo-currency needs to provide value outside of the core group of true believers and if it fails to do so the bubble will pop as true believers eventually fade away and the circle of people who are willing to accept your confederate money becomes smaller and smaller. I see no reason yet to believe that bitcoin will make this transition and a lot of hints that it will in fact fail to make this transition (e.g. the currency is getting too much publicity too early -- it is making itself a target before it has any real social defenses.)