really nice, was just looking at trying to use Jupyter but their JS kernels gave me issues. Being able to use arbitrary packages would be nice, babel transpiling would also be cool.
I think it has potential for use as a way to write documentation for JS libraries, so being able to use arbitrary packages is certainly something I'd like to add. :)
The JSPM CDN could also provide a way to load transpilers like Babel, Traceur, Closure, and Typescript.