Use DefinitelyTyped's React typedefs.
Don't re-render React client side. Use real comments. Much more...

And:
- Make hover-actions work
- Send the current date-time to the client so markup won't change when
  calculating client side
- Include react-with-addons.js in render.js bundle
- Let dummy console functions actually log something
- Some more stuff...
Create one Nashorn engine per core.
Load React's page state from store.
Enable JMX, so can connect with VisualVM.
Missing import, log level.