vawtman,
I have kept an eye on Beaconpower for a couple of years now, I think it is one of the more interesting things coming out of the US in regards to storage. There doesn't seem to be much reporting of it there, though, and here in the UK it isn't mentioned at all. But if if works it could do us all a favour, as leveling out the grid is quite important, and working on the priciple of "a penny saved is a penny earned" we could cut our use of fossil fuels.
They also have smaller flywheels, which might be useful for off-grid storage, but I think they would be very expensive.