Bret Taylor posts that Google has publicly released the Google Web Toolkit, a framework for AJAX web application development.
GWT supports all browsers, does not hork the back button, makes RPC easy and more robust, and can be debugged using the Java debugger. Very cool.
AJAX development by hand is a royal pain, error prone and difficult to debug. The trendy Ruby on Rails owes a lot of its success to bundling with the Script.aculo.us AJAX library to make it super quick and easy to produce snazzy AJAX web apps. GWT appears to offer similar benefits.