Very cool. There are native IPython notebook kernels for Python, Julia [1], R [2], Haskell [3] and now Erlang. Which is why the project is being made even more language-agnostic and being renamed as Jupyter [4].
How easy is it to use the jupyter colabratory stuff with kernels that aren't python?
Should be a matter of configuring IPython default profile to run your lang of choice (ie one line config). Though syntactic coloration and rest won't match but execution will.