Although military action or even escape (remember the North Koreans in June?) has happened in the past, there have been loads of cases where countries have just paid the ransom for their crew and their cargo (and the vessel itself). This was one of those cases.
From AP, via the Washington Post:
Somali pirates freed a hijacked South Korean supertanker and its crew after a ransom was paid, a South Korean news agency said Saturday.AP doesn't cite a ransom figure for the Samho Dream's five South Korean and nineteen Filipino crew members and their $160 million cargo.
The Samho Dream is now sailing toward the United States, Yonhap news agency reported, citing Andrew Mwangura, coordinator of the East African Seafarers Assistance Program.
All the sailors were safe and healthy, Mwangura said, according to Yonhap.
South Korea's Foreign Ministry said it could not immediately confirm the report. It said the release was imminent but the safety of the crew was not secured.