Why we don't believe in "transition" fuels / technologies:
A transition is something that gets us from A to C by going through B. When economic resources (public or private) are invested in infrastructure for natural gas, biomass incineration, biofuels or the like, this doesn't bring us closer to the goal of meeting our energy needs with conservation, efficiency, wind, solar and ocean power. It actually makes it harder to get to our goal. This is because:
Economic resources shouldn't be spent on investments in technologies that aren't the best we can do. Natural gas, biofuels and the like aren't genuine transition strategies. Building an ethanol or biodiesel plant doesn't get us closer to wind and solar, to better mass transit, to electric vehicles... it just uses resources that could be used TODAY to go directly to these solutions.
A good example of a genuine transition strategy is the transition from internal combustion engine vehicles to hybrid cars to plug-in hybrids to full electric vehicles. We can (and should) go directly to full electric vehicles where possible, but hybrid technology has helped make the transition to more efficient vehicles. Plug-in hybrids will be a decent solution for those who need to go beyond the commuting range of full electric vehicles.
These vehicle technologies flow into each other, and can therefore be considered transitional in nature. The "transition" arguments applied to natural gas and biofuels are NOT transition, however. If the technology goal is something available today (if we invest in it), there's no need for investment in "transition" technologies that don't directly build that goal.
As we build the new energy economy, it's better to continue using the existing dirty infrastructure to build the new clean one than to try building NEW expensive infrastructure that we'll be trying to get away from in the coming years. Having that new infrastructure requires that there will be more entities with economic imperatives that will want to keep their plants operating as long as possible, making it even harder to shift reliance once more -- onto the clean technologies we're ultimately aiming for.