AJAX is a new term for an established technique in web programming. It describes an approach whereby Javascript calls are made from a given page back to a web server in order to retrieve small bits of XML for use in updating the page on the user's screen, or even for committing changes to data residing on the server with a web servicem all without any page refreshes.
AJAX programming is not a cure-all, and will not replace page-based navigation of the web, but it will make web applications much easier to use and quicker than when page refreshes are involved.
Scala Infochannel 5 will make use of AJAX techniques in its Content Manager product.
Learn more about AJAX by searching the Scala Website...