Node is V8 and a standard lib. Node is not an abstraction around http (which is what RoR is).
"Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications."
From nodejs.org
Right, and "fast, scalable network applications" !== "http abstraction layer". Node doesn't even come with an http abstraction, it comes with the standard request/response objects that nearly every standard lib ships with.
Node is an abstraction around libev. Http just happens to be the one source of events.