Someone either penetrated Givesendgo to get the donor list or some lazy coding allowed the data to be scraped from the site.
I doubt it - but if it's true that they could access a donor list view through poor security practices then GiveSendGo will have completely lost credibility.
I hope that's not the case. I really do.
They are likely to try to use this info to get people fired by their corporate masters. Like me.