On the Smashing Magazine site today there's a new post introducing you to templating in PHP applications. They cover both the creation of a simple, custom templating library as well as using a more widely known too - Twig.
In this article, we'll cover how to separate the view of your PHP application from its other components. We'll look at why using such an architecture is useful and what tools we can use to accomplish this. [...] To fully benefit from this article, you should already know how to write and run your own PHP scripts on a Web server (i.e. using Apache).
They start with the very basics of templating, mostly pointing out how it reduces the dependency of having layout code directly in your application's logic. It makes things easier to reuse and makes for better code structure in the long run. They mention other templating engines like Smarty, PHPTAL and Twig, but focus in on the last for their code samples. They show basic templating, making reusable templates, applying filters and working with simple control structures.