Ok, is there really a war between them? My opinion is they are currently covering different needs. Rails is a full-stack framework, very mature, used for fast prototyping and full-featured apps. Node.js is more focused on the fast and realtime web. I don't think anybody can get the productivity boost that you can get using rails with any other framework out there. But if you want a really fast and simple API logic, supporting websockets and have some nice specific libraries out-of-the-box, then node.js is a great solution (nginx with lua is also a great solution for websockets btw).
Oh and btw, regarding the speed of node.js, just check benchmarks with eventmachine (ruby) or twisted (python) vs node.js. Node.js isn't only about speed, is also about the supporting libraries they have around it for the specific problem that it tries to solve.