AJAX is a acronym for Asychronous Javascript and XML. The technology is certainly not new, but it’s getting some attention lately to give a more interactive experience to web sites. Flash has had the ability to dynamically pull XML feeds since at least early 2000 and many sites have used this technology in IE via the XmlHttpCallback component.

It will be interesting to see how support grows now that it is getting some public attention.

AJAX Wiki