Get it here
With the Google Web Toolkit, I (mostly a java guy) was able to get a basic 'Hello World' AJAX application running in record time. Eclipse integration is simply great, which brings in the ability to debug AJAX applications in a 'civilized' manner, among other things.
The documentation and the samples were very helpful in ramping up. I'm now looking at the RPC and the surrounding architecture. I think this would be the toolkit that made AJAX 'usable' for a broader subset of developers.
Hope to see great things in the coming days ....