I think a lot of people overestimate the capabilities of Anonymous and the like. Surely there are probably a few in there ranks that actually do know what they're doing, but most are going to be script kiddies, or even lower (basically a human powered botnet operating the LOIC).

I think that what Anonymous does teach us is precisely why it is important to be a good cyber citizen, for all the bad media that will come up if you anger the hive. There's actual security lessons too (you actually need to make the effort to try and eliminate the low hanging fruit, to have security in mind from the beginning, to factor in the risks of a large data loss or defacement).

I think that book could be written by many people in the infosec world, as the details are already public and the attacks are not that sophisticated. The thing is that there are already lots of "best practices" that are not being followed that allow a lot of these hacks to happen. It's true that you may never be confident in how secure or insecure you are, but if you aren't doing the basics (using frameworks that help take care of the basics of things like SQLi, XSS, and CSRF vulns), then you're already behind.