PHP-GTK implements GTK+ 2.x bindings for PHP, namely for those running PHP from the command-line rather than a remote web-server. The Phoronix Test Suite had been using PHP-GTK for its optional GUI on the client-side up until Phoronix Test Suite 3.0.
PHP-GTK developers basically split the project up into several smaller components. There are now static GLib bindings for PHP, a GObject Introspection Generator for static PHP extensions, the GIR wrappings for PHP, static GObject bindings for PHP, a PHP extension for the Cairo Graphics Library, and a Pango text layout engine wrapper for PHP.
All of these GNOME-related PHP components are hosted on GitHub. The GObject Introspection support for PHP is important and was made stable with GTK+ 3 and opens up new development possibilities as detailed on the GNOME Wiki. Cairo and Pango bindings for PHP are also nice for client drawing purposes.
At the end of the day though, this code isn't too well maintained with the latest commits to the GLib and GObject Introspection Generator code-bases being a month old while the other repositories haven't been touched in about a half-year. There's long been coming a new and modern user-interface for Phoronix Test Suite benchmarking, but it's not PHP-GTK based nor based on the technologies talked about within this article. The GNOME/GTK+ support within PHP simply isn't too good at the moment, which is understandable given the primary web focus of the language.