I’m busy working on my first major web site using “Joomla!” 1.5. One of the things I did for the site was to install a simple component that provides an index of articles in a side panel. Simple enough, you click on the index link and it fetches the page with that article.
The obvious solution would be to have the index link send an AJAX request for the relevant content and then to simply repaint the area that needs to change, but that only works in this specific case and it deprives the CMS of the ability to update other parts of the page in response to the request or to other events at the server.
Now the page is an application in itself, and the browser is playing the role of the operating system. The user gets a platform independent, end-device sensitive interface that can be rich, intuitive, and more interactive.
It’s an idea worth implementing. Not for this particular site, but it would be nice to build this capability right into Joomla!