It's been fun watching all the hype fly around AJAX application programming over the past year or so. Especially fun considering that XMLHttpRequest has been in existence since June 2000.Even prior to that, while working at Netscape/Mozilla, I recall considering transferring application state via cookies, over non-page-transitioning HTTP 200 responses. The demands of other Gecko networking layer optimizations derailed any prototyping on that front. That was probably a good thing considering using cookies as a transport mechanism would have been woefully underpowered; hurray for XML over HTTP!
It does make me wonder what really kicked off the AJAX rage (including the acronym). I heard something about someone using the acronym in a blog posting somewhere, and that gave everyone a hook to hang their hat.