They have kind of transcended 4chan. Anonymous is as much a "group" as Al-Qaeda is a "group". They are a small collective of people with like ideals that will (when fit) work together for what they perceive as the greater good. Despite how the idiotic media reports, they are not a collaborative of people with anything resembling central leadership that has a set meeting place. As for their part, this doesn't have the same effect as what Anonymous would go for. They tend to be about informing and uncovering, like a more destructive Wikileaks if you will. If Anonymous were to stage an attack on Sony, it would mostly be a DDoS or stealing and releasing some important information about the company. The general idea behind most attacks from Anonymous is to hold people accountable for their actions, this attack on the other hand was deliberate fraud. The people found an exploit, and decided to use it to try and steal some money/information.