[jQuery] Java integration

[jQuery] Java integration

This was mentioned on another thread, and there were at least 2 other people interested in it, so I think it warrants its own thread.
What are people's thoughts on some sort of jQuery integration with Java on the server side? This is exactly the setup my company runs, and we'd be interested in investing some resources in building such a thing, but I don't really see the benefits.
Maybe something to tie in client side validation with Hibernate Validator?
A nice thing about javascript libraries like jQuery is that they tend to use JSON and/or XML on the wire, so communication is nicely abstracted away from a particular language/framework on the server side. And the web framework we're using (vraptor) already does automatic JSON and XML serialization. So what else is there?
--Erik