The SAE J1772 is more than a cord cap. It's called a coupling (625.16).
It is part of some new standards that will come with the electric car. Part of the above is SAE J2847/J2836 Communications Standard (comunications over power lines) for electric cars.
Follow the link to what looks like a GM training documents overviewing the Volt electric car:
http://www.ieso.ca/imoweb/pubs/smart_grid/GM-TomOdell.pdf
From Page 16:
NEC Article 625
Comettee work underway
Replacent of terminaligy "charging" with "power transfer" to recognize potential of an EV as a source of power.
Look at 625.26 Interactive Systems
Electric vehicle supply equipment ..... also serve as an optional stanby system or an electric power source. Article 702 or 705 shall apply.
To sum it up it with this tecnoligy in place it looks like to me:
The utility will be able to adjust your car charger to adjust for their grid load
The utility may be able to use the EV to backfeed the grid
The utility will be able to charge different rates for EV and different times of day
Their may be plans for a road tax on the EV electricity used
The EV owner could be identified for billing puposes at an other than home location (roaming) within the same utility operator
The utility can identify the type of location that is charging the EV
Perhapse stolen EV or their drivers could be located when pluged in with this tecnoligy