<iframe> element, or by use of the
XMLHttpRequest object in more modern browsers.
I think it’s just a “right time, right place” thing. It’s only been recently that big commercial companies have started using the technique for applications that are in the public eye. And that’s because it’s only been (fairly) recently that you could count on a significant percentage of web users to have browsers that supported it. Five years ago, there were still a significant number of Netscape 4.7 browsers out there. Internet Explorer 5.0 was still fairly young, and there were plenty of IE 4 and even IE 3 users. But now? IE 6 and Mozilla 1.0 dominate the browser landscape, and Safari is the king of the Macintosh hill. Basically, the web environment is much better able to support remote scripting now than it was five years ago.
So, sure, Ajax is “old wine in a new bottle”. Let’s not get hung up on the name. But, personally, I think that “Asynchronous Remote Scripting Engine” would have been great. Then if you were debugging your rich client application, you could complain, “I’ve got bugs in my ARSE!”