Elizabeth Smith has created an automated system that generates a complete installation of PHP-GTK2 and PHP5 on a local (Windows) machine.
They're almost working - I'm still trying to coax xdebug to build properly, I have libglade and scintilla php-gtk extensions that work perfectly, gtkspell and gtksourceview extensions that work but spit glib errors to the console (they don’t die though, and that's all that matters), and a gtkmozembed extension that builds but crashes whenever you try to load a url.
You can check out the latest builds on callicore.com including the libraries she had to include to get things to compile correctly (zip archives).