There is a new project (currently in .01 status) called The Dojo Toolkit. From their site, the goal is to “create a UI toolkit that allows a larger number of web application authors to easily use the rich capabilities of modern browsers”.
There is also an Introduction to Dojo on the site that explains what they are trying to accomplish.
The project is in it’s really early stages, but it looks interesting.
Also interesting is that this is another project using Trac for their project management software, something I had written a note to myself about previously (3 months ago to be exact), but still haven’t made the time to get it installed.