Power Meters / Powermeters (SRM, Powertap, Quarq, Ergomo, Vector, Stages, power2max, P2M, 4iii, InPower, Cinch)

I have only used for cycling as I never did anything else. I would like to know how does it work for running but I know very little about running training.

If people want to learn about training with a PM, I think that the best is Training and Racing with a Power Meter by Andrew Coggan, Hunter Allen

Popped round a mates house to check over a rear wheel last night, and he'd just recieved that very book. Seems widely recommended.