From FP's Situation Report:
Piracy has plummeted off the coast of Somalia.

Citing Andrew Shapiro, assistant secretary of state for political-military affairs: "This multi-pronged strategy has led to results...We're seeing more pirates prosecuted, fewer ships being attacked, the statistics are striking."

According to the (US) Navy, there has been a 75 percent decline in overall pirate attacks in 2012 over the year before. And the number of attacks in 2011 were half that what they were in 2010. Independent sources (for) Last year, pirates captured 10 vessels, compared to 34 in 2011 and 68 in 2010...and the last successful attack of a commercial vessel was in May of last year. In January 2011, pirates held 31 ships and 710 hostages; today, pirates are holding four ships and 108 hostages.

Despite fears that putting armed guards on ships would create a Wild West, cowboys-at-sea climate, violence has not increased significantly....Once the pirates realize that many ships are a "hard target," they refrain from attacking it, he said. Shapiro also said he was impressed also with the discipline that many commercial vessels exhibit when it comes to using weapons.

Building up indigenous ground forces has also helped. What has really thwarted pirate networks is a ground force known as the Puntland Maritime Police Force, according to an expert who has worked on the ground in Somalia.