I spotted this today on the Ajaxain. Looks very promising! Worth a read.
The UI combines a Vista-like “Start” menu along with an OS X-like dock (using everyone’s favorite fish-eye widget). It also has a built-in widget system that leverages Google Widgets. Overall, it’s a pretty nice implementation of a desktop and windowing in Ajax.
The framework itself is “GwtPHP” which attempts to take all the advantages of GWT and deploy them to PHP backends in an attempt to solve the problem of limited Java-friendly hosting services. Unfortunately, the framework isn’t available for use until sometime in early November.
GwtPHP is a complete solution Unlike most of the other frameworks, GwtPHP is a framework for both client and server part In GwtPHP you don’t need to hack JavaScript, you work with modern, object oriented languages. User intefrace (client) is programmed in Java, then compiled by Google Web Toolkit (GWT) to browser-dependent JavaScript. Server part uses PHP 5 - the most used web scripting language today.
Dual-License The developers intend to use the familiar “free for hobbyists, pay up for commercial use” licensing model (what their licensing page calls a “what for what” model).
Give some feedback: They are quite keen to get feedback from folks on the project, so interested folks should get in touch, let them know what you think about the licensing model, and perhaps get early access, etc.