Look i'm sorry :-) I did not want to spark this discussion and it is not like AI War is aiming for realism. From a physics point of view, the first thing to object would then be the movement of space ships and fixed structures around a planet or even spider turrets. I mean...if you kill the engines of a space craft it does not stop. It keeps on moving, and moving, and moving...
So i was basically yammering about lightning in space where the lightning supposedly visuallises flowing current (or as keith words it- charge delivery). Because the glowing jagged lines (in air such as during a thunderstorm) is a glowing plasma of heated gas as the current flows through the gas and additionally without medium there cannot be any current in the first place.
I liked the idea of an artifical medium, although the Faraday-Cages probably would protect the ships even without warning. If the hull is conducting, the current will flow around the ship (but through the hull). If the hull is not conducting the current will flow around the ship (through the artificial medium). After the attack most of the ships will then probably be charged. This probably wouldn't have any larger effects as the inside of any charged object is free of electric fields. (The ships would repel each other though :-) ).
Also, just to clarify: Electricity - electrons, electromagnetic waves - photons
As for the drift speed vs speed of electricity the analogy of a garden hose explains the difference quite elegantly. Imagine a long garden hose (filled with water). Now you open the faucet and water will almost immediately pour out of the other end. However, it will take some time until the water that just left the faucet reaches the end of the hose.