Wan Qi Chen has started a new series that looks at using PHP port of the resque (a Ruby based tool) to do background processing for parts of his PHP applications - PHP-Resque. So far, there's three parts to the series (with one more on the way):

• Part one introduces the idea behind working with a background queue, the general workflow a process would follow and some of the benefits/drawbacks of using them.
• In part two he gets more into the actual queue system and discusses the concept of a "job".
• The third part gets more into the implementation and helps you get the PHP-Resque, predis extension and the process control extension installed.

The fourth part of the series (pending) will get into the actual code to implement this system you've job installed.