As much as buzz word this has been, in reality AJAX is really an outdated technology these days. Here are the technologies that have surpassed it:
JSONP does not really XHR request, allows for cross-domain loading, and in many browsers parses faster.
WebSockets seems to be the new "ajax" paradigm for server/client communication. While this feature is not full available in all browsers, there are frameworks such as socket.io that have workarounds for older browsers, so this feature is ready to use.