The U.S. Navy has been embarrassed by the Somali pirate situation. After a decade of preparing for "littoral warfare," the navy finds itself largely winless in its first major littoral campaign. The piracy situation in Somalia is basically unwinnable as long as no nation wants to put troops ashore to shut down the coastal pirate bases (about eight of them). So risk (or bad PR) averse are the navies that even killing pirates is avoided (and rarely done). Pirates are not even prosecuted in most cases, just disarmed, fed, given medical treatment, and released.
The U.S. Navy has hundreds of destroyers, frigates and amphibious ships it can apply to the Somali situation. But many other nations want to get involved in protecting the quarter of the worlds' shipping traffic that passes Somalia each year, so the U.S. Navy has not been able to pile on. Just as well, as the current rules of (non) engagement would just frustrate more American sailors.
The U.S. Navy has also built a large force of naval infantry over the last five years. These brown water sailors saw some action in Iraq, but are not being prepped for any duty on the Somali coast. The asymmetrical warfare the navy has long prepared for turns out to be controlled more by the State Department and international public opinion, than any wily foe. Then again, many naval officers consider the State Department and international public opinion just more hostile, and wily, foes that have to be dealt with. But right now, the diplomats, spin masters and pirates are winning.