There’s a problem if one is using the NPM version of React, and kadira:react-layout. It’s because the latter is including the Meteor React packages, and if you try to do something like <input ref="hello" /> in a component, an error is thrown that talks about two instances of React being included.
I’ve worked around it by just creating /lib/react-layout.js and copying this file into it, then removing the kadira:react-layout package. I assume at some point, kadira:react-layout will be copied to NPM’s registry.
Error details: https://gist.github.com/jimfb/4faa6cbfb1ef476bd105