Kevin Schroeder has a new post today sharing some of his experience with the Zend Framework 2 Event Manager in a simple example of pre- and post-validation hooks in a model.
I got to play with the Event Manager. I did like the plugin functionality in ZF1, but it required some pretty static coding. In some cases, like the front controller plugins, it makes more sense (though this way seems more desirable). [...] It's a ZF1 application, but since (it seems) the event manager is self-contained (and the autoloader works with both ZF1 and ZF2) you can simply paste it into your include_path and BOOM, you have an event manager.
In his case he has a set of models extending a base class and wanted to introduce pre- and post-validation hooks to make it simpler to check the data he was working with. He includes the code for his base model class showing how he implemented the ZF2 EventManager in his ZF1 application. He attaches an event to the password class property and, on update, it automatically updates a temporary password value too.
You can get more information on using the EventManager in this other post from Matthew Weier O'Phinney.