From Leon Pegg on the PHP-GTK Community site:

I have been working on the php-gtk documentation the last few weeks. I finally have an updated version of the manual. Unfortunately its not on the main site gtk.php.net, so I have uploaded it here: leonpegg.com/php-gtk-doc

The manual includes tutorials, the actual reference guide and an appendix of details on terms/other information.

PHP-GTK 2 is out, and with it, a fantastic means for PHP developers to build useful, reliable cross-platform desktop applications. In this tutorial, I'll show you how to get up and running with PHP-GTK in no time and build your first desktop application.

They look at qhat it is, getting started with it and making your first application (a simple little "Hello World" output box). They also point out some of the demos you can grab as examples and show you how to make something a little more powerful - a window with an input form that generates an md5 hash.