Thanks to Hoz for opening the discussion by posting the article.
I cached a couple of the thunderbolts threads on electric comets (see
On Other Sites), in case somebody wants to glean more info from them. If anybody knows of additional threads, let me know, so we can have a more comprehensive list of relevant resources.
Just to kick off the discussion here, as I recall, Brant & I are in agreement that there are definitely electrical effects on the surfaces of comets, and in the comas, but we were thinking that it was photo-ionization that was eroding the surfaces, not EDM.
It's also possible that comets have positively charged sheaths, partly because the heliosphere has a slight positive charge, and partly because of frictional ionization. So the "etching" that we're seeing might be more than just photo-ionization — it might be assisted by Coulomb repulsion in a positively charged body.