I'd be interested in knowing the details of the attack. Was it a "social engineering" attack of some kind (ie. a virus-laden email that someone with high privileges opened)? Was it a vulnerability in their networks? I've heard someone with high level admin privileges had their account hacked, but in what way was it done?
The organization I work for is a contractor for the government of a North American jurisdiction, and yesterday morning I started getting reports that some sort of virus-laden emails were flowing out of this government's networks. Sure enough, within a half an hour, I got emails from a contact I have within this particularly agency, with an attached ZIP file with an SCR file inside. That has to be one of the oldest ways that malware has been transmitted in Windows system, I saw my first virus-laden SCR file somewhere around 1997-1998.
Apparently this critter is so new that by the time we checked, only a few AV companies had caught on to it. Even worse in some ways is that it appears that it made its debut on the very government servers in question, making me think this was a targeted attack. So you have a combination of a brand new virus of some kind that won't get caught by the scanners, lax email rules that allow the opening and execution of executable file types (not that blocking EXE variants doesn't mean some bastard won't be firing off a compromised PDF at an unpatched system), and users who through a combination of laziness and ignorance happily take the final step.
With this particular attack, there would have been no problem if Outlook had been configured not to open these kinds of attachments, and in an Active Directory environment, that's pretty trivial, so some of the blame has to go to this government agency's IT team. But still, even with the best safeguards, where users just happily click on any old attachment, it doesn't exactly take a rare alignment of the stars to have malware planted in a network. Sure, it won't have root privileges and won't be able to propagate itself via more sophisticated means, but it appears in this case it didn't need to.
So I do agree to some point that there are finite limits to what any person or organization can do to secure itself against a determined and directed attack. But there are ways to make such attacks much more difficult, and more quickly captured before they wreak too much harm.