Elizabeth Smith has posted a new item to her blog today with information about a PHP-GTK2 framework that she's been working on (and with) called the Callicore Desktop.
Don't look at me like that, I haven't lost my mind. It's not really a framework in the traditional MVC web application sense. Instead it's a group of fairly loosely coupled widgets and classes with an emphasis on clean code.
With the help of several singletons, multiple widgets and a modular structure, the Callicore Desktop makes working with this parts as simple as calling it on the command line (with limited setup). If you'd like to get a look at the current version of the framework, check out the Callicore site or just head straight to the code.