First, let's stipulate that 4chan's Anonymous raids are mostly juvenile and often ineffective at doing anything meaningful to their targets.
At the same time: The ability of a community to completely self-organize, without central direction, and instantly execute a publicly-visible plan like this is without precedent in human history.
It stands to reason that as time goes on, larger groups of people will become involved in communities that exhibit 4chan-like cohesion. A larger pool means a higher likelihood of these groups including people with the knowledge and ability to do ever-increasing damage.
The long-term implications are interesting. Into the future, are we talking about the instant formation and dissolution of "terrorist" or "dissident" groups, bound together by transient common interest and gone again within days or hours? If you're a government or corporation, this is terrifying. You can keep tabs on other governments, and even traditional terrorist cells, which each move at the speed of the usual group dynamics, proportional to their size.
But what the hell do you do about groups you can't predict that are gone before you even figure out what's wrong? Groups that aren't bound together by national identity or other easily quantified affiliations – just ideas, ideals and transient events?
There's something meaningful here that points to how we all get along in the future, in the same vein as the "post-secrecy world" presaged by Wikileaks-style activism enabled by network technologies.
Or maybe I just need a nap.