In reply to toad:
Yes. Pit Schubert's classic book on alpine safety has an entire chapter on thunderstorms in the mountains. Bottom line: you do not only have to consider the point where the lightning strikes, but also the path that the current will take down the flank of the mountain.
Via ferratas are obviously particularly bad places to be in as they are a nicely paved path of least resistance, even if the lighting struck quite a bit higher up. As an interesting and counter-intuitive aside, sitting a thunderstorm out in a cave or underneath an overhang can be more dangerous than staying outside in the rain, depending on the dimensions and location of the cave. Reason: the current might decide to take the shortcut through your body instead of taking the long way through the back of the cave.
If you get caught in a thunderstorm in the mountains (which you should of course avoid in the first place) then a relatively safe place in terms of lightning strikes would be an open hill side well below any ridges.