This new PHP extension is called "GObject for PHP", so, my main concern, obviously is building comfortable bridge between GObject objects and PHP's objects. It starts to work, but there's a lot of stuff to be done. Please join the project, if you are interested. We need more hands!

He describes some of the features already in the library - counterparts for parts of the current GObject world in PHP including GType, GSignal and GParamSpec. This is all on the master branch. In his "introspection" branch he's working on the introspection idea the GNOME community has been working towards too.