On the SaniSoft blog there's a new tutorial where Jatin Chimote introduces you to the world of building desktop applications with the help of the Appcelerator Titanium software.
The post is about creating desktop applications with the help of PHP. And No, we are not using PHP-GTK. You can now create desktop applications without learning a completely new programming language! That is with the help of a free and open source tool called "Titanium". Whats more you will use your existing CSS and Javascript and PHP knowledge.
They introduce the different parts of the Titanium platform - the Desktop SDK, Mobile SDK and Developer tools - as well as explaining what it takes to use them and what you'll need to download to follow along. They take you step-by-step through the process (complete with screenshots) of making a basic "currency converter" application using the Exchange API to to the heavy lifting.