While the press will blame the companies, it's the humans that are the weak link
"The ZeuS variant does not exploit a vulnerability in the Salesforce.com platform itself but rather penetrates the insecure devices of corporate workers accessing Salesforce.com."
Standard stuff -- why sweat over trying to brreak in through the front door when there is always someone leaving a window open somewhere for you. 'I only had a fag in the bathroom -I was sure I shut the window'.
I really hope they don't make machines to behave like humans -- we're buggered if they do.