I had serveral short AJAX articles in the last weeks and pointed out, that a standard approach to AJAX is the only hope for that technology. If we end up in a IE AJAX and a FF AJAX, we will just pull out the old stupid browser dependencies again. These dependencies are not yet overcome and if you ever surfed the web an a WebTV, you probably know, what I mean.
Yahoo! tries to help developers with a new set of libraries for AJAX designs. If you are a webdesigner, you should look into that!