So if it's powered, first thing what get in my mind is that, this'll use energy.
It would be a good electrical alternative to minecarts. Although it should require power, maybe a mechanism akin to EU loss in cables. That way it becomes adequately difficult to build this sort of thing over large distances.
Or perhaps, like the Electric Ladder idea, have it use RE/SU batteries, or if higher EU is needed, use Energy Crystals/Lapotrons (overkill, I know)
I really don't think that it should be powered, or consume eu, or whatever. We can just say that each block have some energy from the beginning (from some amount of redstone or uranium mixed in), that lasts effectively forever.
If we really, really want it to use eu, I think simplest option is to treat connected lane blocks as a single body, that consume energy per player using it/second.
That would require the program to check constantly if/how many players are on it at which point. That seems fairly cpu intensive to me. If it was calculated along the lines of wiring, it shouldnt take more cpu than the new revolutionary wiring code and would balance near/far transport. Using expensive building blocks would make this too difficult to obtain for short distances.
I've already coded "Electric Ladders" in form of MetalFences.
MetalFences can either be used as that (fences) OR to create "Poles". Poles will have a true collison box (not a whole block) and can be used as "fast downwards" way... jumping against one and holding shift will cause Steve to slide down at mediocre speed, without fall damage. It's faster then a ladder and could replace water-dropshafts.
Additionally, you can create a Magnetizer block. If places below or above a pole, it will charge up a pole of max 20 length. Charged poles will accelerate players upwards (quite fast) if they are wearing metal boots (Iron, Gold, Chain, Nano). Without metal boots, they act as casual poles.
I've had loads of fun creating "Obstacle parcours" from this, where you had to use momentum and stuff to get from pole to pole 
Redirecting to the Original Electric Ladders.
