It seems a bit soon to have determined the source. The problem with DOS attacks is that the source may be quite different than what it appears at the onset. In any event we will likely see more of this in the future. It would be nice if Hosting Matters released a statement about the nature of the attack. People are jumping to all sorts of conclusions about what the attack was and from where it originated. They almost have a responsibility to do so yet I can imagine many varying business and technical reasons for why they wouldn’t.