Well, once again according to the Faq on the website that Baron linked to, the current flow from the electrical diferential would be negligable. They kind of skirt the lightening issue by simply saying the best way to avoid lighetning strikes is to have the cable in an area that has a low histroy of lightening activity. That doesn't really say though what happens if it is hit.
I guess the ribbon itself won't be used for powering the climbers as I thought originally. They are suggesting photo cells on the climbers and use a ground based laser aimed at the cells to power the motors on the way up and down.
Geoschmo