In Matt Curry's most recent blog entry he looks at the creation of a CakePHP plugin that integrates Yahoo! Search BOSS (Build your Own Search Service) into an application.
I mention that Neil's code would make a really cool plugin. This sparked a discussion as to whether this was possible with Cake's current plugin architecture. The issues where: how to get the datasource configuration, which would normally go in /app/config/database.php, how to reference the datasource class itself and how to handle the custom route.
The created the plugin with a ConnectionManager instance that goes out and loads in a configuration file inside of his search model in his application.