That's a nice collection of links. I'm not a big fan of AJAX, as I like web stuff server side and local stuff client side -- I don't like mixing. AJAX also dramatically decreases the flexibility of an application, typically alienating users who disable JavaScript and users on portable platforms. Since no two browsers have identical JavaScript implementations, developers typically pick one or two platforms to support and alienate the rest -- making the web less accessible in the name of making it seem more responsive.
All that aside, it is a cool hybrid technology that is a must-know for anyone in the web development industry -- it's not going away any time soon, and people are already expecting every new web-ap to act like it isn't a server side application.