Most owners of electric cars will be able to plug them in overnight and/or during their work day almost every day, so for most trips, the battery will be full. But what about for longer trips that exceed the roundtrip range of the battery? It's in those cases that fast-charging stations become crucial, and what matters most in those cases is how fast they can pump electrons in the battery, and how conveniently they are located.
Tesla CEO Elon Musk has revealed that the first of these "super-chargers" will be located between Los Angeles and San Francisco, that they will use 90kW chargers that can add about 150 miles of charge to the batteries in 30 minutes, and that they will look kind of like "alien artefacts". More details should be known about the exact location and tech specs in early 2012.
This is obviously a very strategic location for Tesla, as most of its current and future customers will probably be living around these two cities, at least at first.
The upcoming Model S will have battery swapping capabilities in case that ever becomes popular, but for now Tesla seems to be counting on fast-chargers and the fact that the car can be ordered with a bigger battery pack that can give it a range around 300 miles, which should be enough for a majority of trips.
I would be very surprised if battery-swapping stations took off. By the time it will take to build enough of them and make sure that most electric cars on the market have battery-swapping capabilities, battery technology will probably have improved enough that range will be less of a problem, and fast-charging stations will be much more ubiquitous (they are technically easier to build than swapping stations). We'll have to wait and see...