Robert Basic has a new post to his blog today with an use case for Zend Framework 2's event manager to solve a problem he has with "repetitive code" in some of his models.
Basically, this allows us to have one piece of code to trigger an event and to have one or more listeners listening to this event. When the event gets triggered, the listeners are called and then we can do *something*, like caching or logging. Logging or caching. [...] See, that’s my problem. All the event examples stop at logging and caching. Truly there must be some other example for which this event stuff can be used for.
In his example code, he's used the EventManager in one of his models to add listeners to validate the post and "slugify" the post's title for use on the URL. You can find his code on github if you're interested in the full implementation.