On PHPBuilder.com today, there's a new tutorial that takes a beginning look at PHP5's class inheritance model.
There are many benefits of inheritance with PHP, the most common is simplifying and reducing instances of redundant code. Class inheritance may sound complicated, but think of it this way. Consider a tree. A tree is made up of many parts, such as the roots that reside in the ground, the trunk, bark, branches, leaves, etc. Essentially inheritance is a connection between a child and its parent.
They choose to go with a "car" illustration instead and show how a child of the Product class (Car) can access the private properties of the parent. They also include an example of it in action with a bit of HTML output.