Ars Technica reports that sources within Sony's hosting provider belittled Anonymous' cyber-attack as "medium strength", and something that only "annoyed our network engineers". The hosting service's plan is to wait out Anonymous until the attackers get bored.
Sony sites have gone up and down through the week, to the point that Anonymous called off an assault on PlayStation Network, considering gamers using the service to be blameless victims. But the network engineer Ars quoted said sites only went down early in the assault, as they maneuvered to block what was a large number of incoming IP addresses carrying out the attack. Sony's jobs site is reportedly the current target.
Since the blocks went into place, it's been mostly smooth sailing - though Sony has contracted with the cyber-attack mitigation service Prolexic to keep its domains running. Anonymous evidently has experience attacking both Prolexic and this hosting provider.
Anonymous, offended by Sony's conduct in litigation against the hacker George Hotz, initiated the attack earlier this week. Sony yesterday conceded that an outside cyber-attack may have been the source of network outages this week, but didn't blame Anonymous specifically, probably not wishing to give it publicity.
Source: Anonymous attacks on Sony annoying, not much more [Ars Technica]