Why not a Third Party?

Over on Centroids, we're have a spirited discussion about the necessity -- and impossibility! -- of starting a third party. While Unity '08 explicitly avoids this goal, I suspect it will face many of the same issues. In particular, I agree with Billy Rojas's claim that you need both a Personality and Platform in order to generate a viable movement. Unity '08 -- as a neutral middle ground -- starts with none of these, though there is still hope that such might emerge...