The FBI has been conducting search and seizure warrants and also arresting suspected Anonymous members across the Nation.
As things have it, everything is traceable within the computer world. Only a very smart few can "live forever" but that is being dwindled away as well.
With so many Hackivists claiming to be part of the Anonymous group, trails are made. Sooner or later these trails will lead the Feds back to you.
So if you value your systems and knowledge, be careful, nothing is truly anonymous anymore.