That's curious. I've seen some widgets or apps that don't uninstall via an uninstaller. Maybe for the pirate widget you have to go to settings>application>manage, find it there and click "uninstall". I've found a workaround for this and not only. After a session of market and loads of app downloading, I use the Shake Uninstaller. I open it, I run the apps I've installed, and if I don't like them, I just shake my phone (literaly) and the app uninstalls. The drawback for widgets is that it has to have a settings menu or any kind of menu, in which you can shake your device.