OK, NodeJS is all the buzz these days because it handles things in a non-blocking asynchronous way. Because of this, it is very well suited to being a server of some sort, handling requests from multiple clients concurrently. So my question is whether it would make sense, from a technical perspective, to write a general-purpose Rails app AND web server for production use. To be clear, it would take the place of (for example) Apache and Phusion Passenger. Would this setup, in theory, not be faster at handling requests and responding?
You could use Nginx, Lighttpd or Mongrel2 that are event based and probably still keep your Ruby on Rails. To my knowledge, all three of those use event I/O and don't build and tear down threads or forks on each new connection. This way, you can keep your Ruby on Rails. If you need bidirectional communication for any AJAX, then I'd suggest putting in a Node.JS Socket.IO server.