Grails Quickcasts, brought to you through a partnership between Object Computing and DZone, provide bite-sized tutorials to help you maximize your productivity with the Framework.
create-interceptor actually creates an interceptor. Mind. Blown.)
This Quickcast assumes only basic familiarity with Groovy (which is pretty darned expressive anyway) and the MVC concept (which you already know). It also serves as an excellent introduction to the interceptor pattern in any language, because Grails' behind-the-scenes legwork lets you focus on the logic of the pattern.