Callicore is a PHP-GTK2 based application framework. What's the difference between this and a traditional framework? Callicore is worried less about flexibility (make everything work) and more about applications (do the hard work in a structured manner). Version 1.0.0-alpha has been released. The source is available via subversion. Callicore is designed for php 5.2.x. It may seem odd to have a framework for a desktop application, but CC is designed to make even difficult things like configurable toolbars or tooltip management easy and fast.
Callicore has two mailing lists, one to keep track of svn commits and a developer list for those wishing to get involved with the callicore project
There are currently three applications built on Callicore. Writer is a fiction writing helper. Ide is a basic PHP and PHP-GTK ide. Photo is a simple photo management and manipulation tool. If you have an application built on Callicore and you'd like svn hosting feel free to contact me.
Callicore currently requires the "latest and greatest" version of PHP-GTK2 and the GTK 2.10 or better libraries. Support for this is currently in CVS. If you're on *nix this means you'll probably need to build PHP. If you're on windows you can find what you need at Perisama which is devoted to building open source on windows.
There is no current timeline for releases. If you'd like to be involved with any aspect of the project, or want to ask questions, submit bugs, or ask for features please join the development mailing list above and speak up.
I'm usually on IRC - freenode on #php-gtk if you want to become involved in the project or just have a question