If I was a realpolitik US official, I'd work out a UN-sponsored peace-keeping trip to Somali (bankrolled by the shipping magnates who suffer from this) and start delivering plenty of high-explosive peace solutions to the pirate bases. As an added bonus, the expedition can be used to keep the Islamists from gaining control of Mogadishu and even turn back their expansion in places. The only tricky part is getting the manpower - perhaps China could be enticed to help? They would also be less concerned about casaulties, from a historical standpoint...

Of course, I don't really advocate this personally, but it would probably slow down the problem.