Responding to this FP blog post about the global silence that ensued when Turkey invaded Iraq to attack the PKK....
Certainly Baghdad cannot take many concrete steps to counteract the incursion, but just as wise public companies telegraph their moves to the stock market months or years in advance, Turkey did the same to the world.
In addition to words, the Turkish military started with small, infrequent missions. Over time, the frequency and potency of the military incursions increased. This slow-build strategy gave the world plenty of time to analyze and debate this new conflict -- while the conflict was happening in real-time, albeit slow motion.
If that were not so, one would assume the [non-PKK] Kurds would be making far more noise, including making life ever more difficult for the fledgling government in Baghdad. Shia blocs may dominate the government, but the Kurds retain the ability to throw a hefty monkey wrench into the works.
Branding the PKK is officially as a terrorist group enables additional avenues of pressure due to the War on Terror, pushing Iraq (particularly the Kurds) into grumbling non-action.
Also: Though I haven't seen much written about this, Iran also appears happy to give Turkey a free hand.