In the first three months of 2013, more people bought Tesla Model S electric cars than equivalent (more or less) models from Mercedes, BMW, and Audi. Obviously, these aren't very high-volume models, but still, not bad for a company that wasn't making any cars at all a few years ago. It shows that Tesla's strategy is working. If you make a really good electric car - Consumer Reports called it the best car they've ever tested - you can easily go head-to-head with gasoline models and beat them. That's important, because in some places (ie. big cities) cars don't make much sense and we should make more efforts to improve walkability, bike lanes, transit, etc. But outside those big cities, people will be driving for a long time to come, and electric cars will make a huge difference, especially as our power grid becomes cleaner over time.
So hopefully when Tesla comes out with its third generation platform in a few years (the first was the Roadster, the second one is the Model S and its derivatives like the Model X), they can compete with high-volume mass-market models and push forward the transition away from oil in transportation.
In the meantime, remember that the biggest difference you can make is not driving. But if you have to drive, it's best to get the most fuel-efficient model that meets your needs.