I think that the hacked FBI phone call is a good example of how they work.
From the info that was released so far about it, it was just a guy that had hacked a random gmail account, found an email with the call details and then told Sabu about it (which at this time was already working for the feds apparently) and asked him for help with a VoIP software to record the call and distribute the phone call.
I believe this is how they always work, some guy does something and then they put the anonymous stamp on it. It's wrong to call this an organized group or to suggest that there is someone pulling all the strings behind the scenes, they are just guys doing things, it's as simple as that. I would even say that most of the big hacks are accidental, or at least whoever did them didn't knew what kind of information they would get from it, and are due to the amount of people currently hacking under the anonymous flag, someone will eventually find a pot of gold it they are all searching for it.