If battery manufacturers formed a consortium to define an ISO standardized form factor and operating specs for these swappable batteries then auto makers could make receptacles built in for them. Existing autos could have the receptacles retrofitted into the trunk. The receptacles would probably have to be tailored to each vehicles power requirements and would convert (if neccessary) the battery output into whatever format the car needs. New cars of course could be made to run directly off the batteries. As far as infrastructure goes, you only need as many gas-station-battery-swap-booths as required for the number of swappable-battery-cars in the area.
I was thinking more in terms of a swappable battery pack that is part of a GM-like, modular under-carriage structure. You want the batteries to be low-hanging so as to keep the center of gravity close to the ground. This reduces chance of roll over.

You would drive into an open-trench service station similar to those fast lube job shops. They swap the battery from underneath without having to jack the car up. Maybe they can lube your hybrid car's gas engine at the same time if the car has a fossil fuel burning, booster engine.

Why all the talk about batteries, fuel, etc... and no talk about human powered vehicles?

That's the biggest bang for your buck of all... there must be, all over North America, a huge - massive - number of people that could trade some, or all, of their fossile-fueled transportation for human powered transport.

Too little mind-effort is spent on high tech solutions. Three wheeled bikes with comfy seats, high tech generators (for lights) and cargo carrying capability (on board or via trailers) could easily be mass produced at much lower cost... and given away... and would be far more effective in reducing overall fossil fuel energy use than any other initiative I can think of, other than a mass die off thanks to some new flu virus.

I sure wish I used the preview feature more. I meant of course "too little effort is spent on LOW TECH solutions"...
While i really like the idea of people powered transport, i can only see it being viable for short range, or flat land trips, in weather that is warm enough.