DevShed.com has posted the conclusion article in their "The Iterator Pattern" series (excerpt from this php|architect book).

This article, the second of two parts, explains how to use the Iterator pattern to manipulate any collection of objects.

With Iterators,you can do more than just present each item of the collection. You can also select what items are presented.

They also give two examples of Iterator situations - a Sorter and an SPL (Standard PHP Library) Iterator...