In days of yore, it wasn't uncommon for merchant vessels to arm themselves against pirates. This company in the UK offers a specialized net for use by vessels at risk of piracy:
http://www.apmss.co.uk/ There are many similar anti-piracy security companies springing up; so far they're mostly focusing on non-lethal means of stopping the pirates, but I'm not sure it will remain as such forever, and indeed, many companies offer armed security solutions.
The amount of piracy in the Gulf of Aden is a major issue, but it's not the only hotspot for pirates. Take a look at this map:
Piracy Map 2008 and you can see the other parts of the world with piracy problems, like the Straits of Malacca.
I think the right thing was done in this case, but we're only treating the symptoms of the real problem--unrest in Somalia. I'm not sure we'll have a solution for that in the near future.