We have an indirect, semi-optional, largely accidental dependency on eventlet/gevent which won't work in PyPy, but it's easy to just rip out if we go to production with PyPy. We should rip it out anyway, but there's no reason to spend the two hours on it right now.
What would you deploy with? I have gotten it to work with Gunicorn, but if you can't use eventlet/gevent, that doesn't look like a great option. sync mode works aright, but not as good as async mode.