Some things are a lot easier and less expensive if you have foresight. When you're building a new house, it might cost a few extra bucks (estimates vary from $50 to $200) to future proof it with wiring that can handle the 240v/40 amps required to recharge an electric car relatively rapidly (nowhere near as fast as a Supercharger station, but fast enough considering that most plug-ins spend many hours parked overnight and during work days). But if the house is already built and you need to upgrade the wiring, that can cost a bundle more... It might even be enough to discourage some from even upgrading and replacing their gas-guzzler with an electron-powered ride.
That's where foresight comes into play. Palo Alto has already changed its building code to make sure that new houses will be pre-wired for plug-ins, which was a great idea. So great that the whole state of California is apparently moving in that direction. David Herron reports that draft building code documents contain provisions for new housing and parking lots to have wiring and electrical systems that can handle EV charging.
This new building code could start to take effect in 2015-2016. Hopefully buildings are already ahead of the curve and future-proofing their new buildings already, but nothing can make as big a difference as having this in the official building code that everybody has to follow. I hope that other states (and countries) do the same.
New house buyers should also ask if the wiring can handle 40 amps 240v charging at a minimum. Even if you don't buy an EV for 5 years, you'll be glad you checked when you do...