On the Zend Developer Zone today there's a new post (technically a repost) of an article from Kevin Schroeder about using the job queue in the Zend Server software to enhance the functionality of your application.

When talking about building a scalable application there is a big concept out there that many PHP developers are not overly familiar with. That concept is queuing. It is becoming much more prevalent in PHP-land but the concept of a queue is still relatively unused among PHP developers. [...] Queuing a job is actually very easy to do. A job is run by calling a URL where that job resides. The Job Queue daemon will receive the request from your application and will then call the URL that you specified in the API call. Once you call that URL your application can continue going on its merry way to finish serving up the request.

He includes some code snippets showing how to create the request - in this case a simple call that will just email when the job is preformed. There's more than one way to do it and he includes a more well structured/less scripty way to do things in an abstract class.