Jesse James Garret, founder of Adaptive Path, wrote a great piece entitled ajax: a new approach to web applications. A lot of great apps on the web are based on the methodology, which includes XmlHttpRequest, JavaScript, standard complient design and potentially the use of XML/XSLT. I have been pushing xhtml/css for some time and Ajax seems to be the next step. As Jesse says, what it really requires is a new kind of thinking and it brings more power to user interaction design to the web. Great stuff, and some very good links in the article that go deeper.
Build Ajax Web Applications
