Ancient history lesson here kids, really the only force that can deal with a group of hackers is another group of hackers.
http://en.wikipedia.org/wiki/Legion_of_Doom_(hacking)
http://en.wikipedia.org/wiki/Masters_Of_Deception
http://en.wikipedia.org/wiki/Great_Hacker_War
Also
http://en.wikipedia.org/wiki/Operation_Sun_Devil
Okay this is ancient history I am going to use to illustrate a point. Truthfully I know there are those who claim that Lex Luthor claims the Great Hacker War never happened, but there seems to be supporting evidence, and truthfully I tend to take any claims from anyone claiming to be, or have been dealing with THE Lex Luthor with a grain of salt.
To put it bluntly the goverment has largely been ineffective in dealing with hackers on any signifigant level. Operation Sun Devil was one of the biggest operations in history, and for the most part it had no real effect, being largely a PR stunt, and most of the arrests and attempted prosecutions wound up failing utterly.
The biggest successes the goverment has had in dealing with hackers has come about as a result of hacker groups going at it with each other, and using the police more or less as a weapon to take each other out. MoD and LoD were two of the baddest groups out there, but to put it bluntly they came to some substantial disagreements and there was a battle between substantial numbers of members of both groups, which ended with a victory for MoD and a lot of hackers either "selling out" and going legit as a dodge (internet security companies) or being arrested largely to what amounted to the efforts of better hackers arranging for them to be caught. This (and the wiki articles) are an extreme simplification of things.
Truthfully, groups like the FBI chasing groups like the "Legion Of Doom" around was the stuff of jokes for a long time, especially during the era of BBS systems before the internet as it exists now as in such heavy use. The whole Steve Jackson Games raid (which was mentioned in their GURPS Cyberpunk book, as the FBI wound up seizing shipments of it) being one of the most lulzworthy events, and got a lot of RPG players who formerly had no interest looking at the whole hacker thing with amusement.
The point here is that whether I agree with everything Anonymous does nor not, I don't think the FBI or the goverment can really do much of anything, their track record is pretty abysmal and always has been. Their massive search streak here, and the arrests in the UK, seems very "Operation Sun Devil" like in of the fact that it's done to show them doing something, but I have seen no evidence of anything of substance coming from it. Anonymous is still operating, it's still effective, and there doesn't seem to have been any real convictions, and with the increasingly public/flashy nature of what's going on, if the FBI had something that solid where they even thought they were going to be getting probable convictions they would be shouting it from the rooftops I'd think.
Now truthfully if I was coordinating this for the goverment, and following hacker activity, I'd probably look at other groups with a strong, illegal internet prescence, and see if I could find a way to engineer a war, and use the fallout to get the people involved. Not the best plan in the world, but the bottom line their own tactics pretty much don't work. What you'd really need is another big group of anonymous hackers who use similar tricks to weed out the "hordes of B" and find out who the real threats are. A war between two groups would ultimatly come down to the best people on each side gradually hunting down and trying to
deal with each other.
I'll also be honest in saying that Anonymous does seem like an evolution of the "ancient" groups, that is a huge horde of people for the dangerous ones to hide in. What's more the "we are anonymous" mask tends to be a lot smarter than people using specific handles in their work, so you could say try and track down or trump "the hacker using this name". Way back when that was kind of cool, and gave an illusion of invincibility, but as any comic book fan can tell you guys like "The Riddler" who absolutly HAVE to leave behind personal trademarks (riddles) aren't as effective as those who don't leave any trace, or blend in with everything else perfectly (which is sort of what Anonymous does). Not a perfect analogy, but I hopefully convey my thoughts effectively.
As I've said, I think a lot of what Anonymous has done is cool, but I don't support them in everything they've done, and have never harboured any illlusions of them being a group of philanthropic freedom fighters, due to looking at more of their "body of work" than just the recent events that have been getting them more public attention. I think defending Wikileaks was a BAD move and highly irresponsible for example. The point of this rant however is that I don't agree with those who think that the FBI or the goverment's ire should be something that worries them, because really, it doesn't appear that the goverment has gotten any better at dealing with this kind of thing than it's ever been. I will be very surprised if the US goverment or those of it's allied nations does anything signifigantly effective, because honestly the goverment's techniques have never been all that effective, going back decades now. If the goverment wants to even slow Anonymous down it has to start thinking way outside of the box it's set for itself, I'm hardly a genius and my plan about trying to set up a hacker war to nail people is doubtlessly stupid, but it's ideas along those lines as opposed to conventional security and investigative methods that are going to yield any results.
To some extent I mention ancient history (especially in computer terms) because I think this is one of those cases where we're seeing history kind of repete itself, with the FBI running around chasing hackers ineffectively and setting itself up for a Lollercaust. While definatly differant in both form and function, I can't help but wonder if Anonymous will ever become quite the "Road Runner" to the goverment's "Wile E Coyote" that LoD was.