Sometime in recent weeks, store.apple.com picked up some Ajax. If you didn’t know this either, go play with the online configurator. Notice that as you make changes via the pop-up menus, updates to the “Summary” box in the upper right are made without a page load. The items that are added or altered by your selection are briefly highlighted in blue, which then fades out. Examining the source reveals certain telltale signs as well.
Making the rounds today is a perceptive mailing list posting from Rasmus Lerdorf explaining how simple Ajax really can be. I particularly like this bit: Before you blindly install large “AJAX” libraries, have a go at rolling your own functionality so you know exactly how it works and you only make it as complicated as you need.
Alex Bosworth offers a sensible list of Ajax Mistakes.