[mannykannot]

I'm nowhere near an expert, but the only mechanism that I have heard of for them causing damage is through inducing large currents in long power transmission lines (and, formerly, long telegraph and telephone lines.) I would guess that the risk to electronic devices themselves is less than from a nearby thunderstorm, and that measures to protect from damage via lightning's effects on your external power supply would also be adequate protection from geomagnetic storms.

[bob1029]

This is my understanding as well. The length/scale of the conductive element is directly proportional to how much danger is involved.

The modern power grid has lots of places where it can trip nearly instantaneously upon adverse conditions. Assuming we can automatically trip any segments of transmission, I think most of the damage could be isolated. Long conductors that aren't connected to anything can't cause any damage beyond the lines themselves.

I don't think transformers and generators sitting in storage are going to feel much of anything.