Yes. What ever their intentions, Anonymous use fear as a tactic. Their whole philosophy is 'if you do something we don't approve of, we will hurt you'.
However you may sympathise with their reasoning, that is terrorism. After all, one man's terrorist is another man's freedom fighter.
EDIT: by the way, i use terrorism in it's literal dictionary definition here, aka someone who uses terror as a tactic. i IN NO WAY mean to imply that anonymous' actions are on the same league as mass murder.
However, DOS acttacks, distribution of child pornography and harrasment are all criminal offenses and anyone taking part in those should be prosecuted accordingly.