Shai Agassi has come up with the most brilliant way of speeding up the change to zero-emission cars i.e. electric cars. I believe the biggest hurdle is price. People will say that they care about the environment and the future of the planet, but in reality it's only up to a point. They will always go for the cheaper alternative - as long as the price difference is more than negligible. In his talk Shai shows how you can split the car from the battery and make the electric car more economic to buy and use than one running on gasoline.
However, there's still the issue of battery production and CO2 (and other environmental toxins) linked to that, but I believe you have to start somewhere and he has some really good solutions to how to best get more environmentally friendly cars accepted in the first place. Once the ball get's running we will for sure find better ways to store the electric energy than the current variety of batteries.
I came over an article in Wired today about the startup company Better Place - founded by Shai Agassi. They were showing off their fully automated battery-swap station. Now, if we only can get all the auto-makers to standardise one battery system...