Over on DevArticles.com this morning, there's an excerpt from the new editon of the Sams Publishing book "PHP and MySQL Web Development" that's an introduction to classes.

In this piece, they took the section of the book that gives those new to OOP programming with PHP an inside track to creating useful, stable classes that they can use over and over again. The example that they give is the creation of a "page class" to limit the amount of HTML needed to create a new page. It should allow us to alter the parts that change from page to page, while automatically generating the elements that stay the same.

It's a pretty good starting place, and, though I've never really looked into the Sams books, I might have to check the rest of this one out to see if it's good enough to recommend to friends/coworkers.