This is very true. I made a point to say "the frameworks available for Node.js" above, but I didn't feel like carrying the rest of that language throughout the rest of the comment. Feel free to replace occurrences of "Node.js" with the above language for comparisons to Rails.

Ruby/Node is a pretty fair comparison as far as evaluating "backend server tech". While yes, Ruby is a language and Node is a runtime (thus perhaps making JRuby/Node a more apt comparison), Node.js is far enough removed from client-side Javascript in terms of libraries, knowledge required, etc that I find it pretty easy to compare the two. With Ruby, you find a web framework, supplement with libraries, and code yourself up an app. With Node.js, you do the exact same thing. Good enough for me.