Thomas Fuchs, the guy behind script.aculo.us recently did a presentation in San Francisco about AJAX that looked pretty interesting. He has is slide show online in PDF format here. Associated notes made during the presentation have been put online by the guys at Ajaxian.
Probably the coolest piece of information I did not know about was the link to a very cool window library for Prototype/script.aculo.us enhanced window objects.
At about the same time Google was announcing the immediate availability of their Google AJAX Toolkit for Java. It is interesting in that rather than acting as a HTML embedded AJAX library like Prototype/script.aculo.us is with Ruby on Rails this API seems targetted at Java coders used to writing Swing/AWT (desktop) application interfaces. This does not appeal to me much, I prefer the HTML/controller level coding of Ruby on Rails than writing a completely abstracted user interface in Java. Still the toolset provides a means by which a great many traditional desktop application programmers can start writing for the Internet using a toolset that is very similar to those available on the desktop.