Is it possible to integrate Python and JavaScript? For example, imagine you wanted to be able to define classes in JavaScript and use them from Python (or vice versa). If so, what's the best way? I'm interested not only if this is possible but if anyone has done it within a serious project or product.

I'm guessing it would be possible using Jython and Rhino, for one example, but I'm curious whether or not anyone's ever actually done this, and if there are solutions for other platforms (especially CPython).