Wow, this is actually quite big. I'd say, more significant than the previous decision by Poland (and then other EU counties) to suspend ACTA ratification. Suspension meant merely that they needed to think more about this. Now Poland comes out openly _against_ ACTA, and that's a _first_ among the participants and signatories of the treaty.
Congrats to the participants of the anti-ACTA protests in Poland (possibly the biggest ACTA opposition in the world), who brought about this change.
Well, despite all the "juvenile behavior", Anonymous is a force to be reckoned with. They mean it when they say "Expect us.".
I also think the fact that they don't care how you perceive them (by acting juvenile or otherwise immature) is one of their greatest strengths. Believe it or not, but it frees you from a lot of burdens if you don't have to be polite and politically correct, and makes it a whole lot easier to actually do something (whether or not that something is good and/or justified is certainly debatable).
Congrats to the participants of the anti-ACTA protests in Poland (possibly the biggest ACTA opposition in the world), who brought about this change.