incrediBILL - 3:41 am on May 28, 2012 (gmt 0)
Did a little bit of quick recon and all of the domains mentioned above that I checked were being hosted by akamai.com so maybe it's possible the issue is with their managed hosting.
Here's why I think this, check out this page about about another hosting client, festival-cannes.com [akamai.com...] and guess what, without the "www." on that domain doesn't resolve either!
My gut tells me there's just a checkbox on a managed dedicated server control panel for " www" that nobody checked and is unchecked by default.