Alexander Gewessler, a co-developer and friend @ diamonddogs, has released a javascript library for "accessible rich internet application", based on the WAI-ARIA working draft from the W3C.

From his website:
Embedding Accessibility in Rich Internet Applications is of great importance for achieving the goal of Universal Design, the approach to design products that can be used by all people without the need for adaptation or specialization.

Website: www.access-see-be.net

The source is also available at github.