How to convert a commuter CX bike to an Electric bike?
I live in the southern most part of Nashville, TN (quite hilly with a major hill between my community and the rest of Nashville). I ran into @Blam's point exactly and have been considering investigating this new technology.

http://senseable.mit.edu/copenhagenwheel/index.html

The weight is the lowest comparable to other options (battery variable).
TOP SPEED   US: 20 mph, EU: 25 km/h
BRAKE TYPE  Rim brake and regenerative braking (downhill and back-pedal)
WEIGHT  5.9 kg / 13 lbs
DROPOUT 120 mm (single speed), 135 mm (single speed and multi-speed)

I haven't ridden one yet but it may be worth investigating.