The WSJ doesn’t provide many details apart from that “a highly sophisticated hacker” got in earlier in the day, and that the server was “wiped out” though “no data was lost or stolen.”
A word of caution: campaigns have been known to blame those mysterious and omnipotent hackers when things go wrong. (See. Lieberman, Joe, 2006) Much less embarrassing than admitting that it was your own fault. More likely would be that someone got in on a more typical vector. FreedomWorks.org appears to by a typical Drupal site; if so, they may simply have failed to keep it patched up to current.
I’d be surprised if professional-grade hackers were involved. While they may have been offline during an important time, I see they’ve still managed to raise $200K for the Beck fundraiser that was supposed to have been disrupted.
This indicated one of the reasons to not overplay the threat of hackers, by the way – if someone blows up your house, well, that’ll take a while to fix. If the wipe out the contents of your server, if your sysadmins have done their job well you’ll be back online in hours.
It’s also possible that activists opposed to FreedomWorks’ agenda were involved – anything’s possible – but as that’s what the group would like you to believe I’d have to see some credible evidence before thinking it was more than a malicious vandal.