The product that I'm currently working on, Stre.am, runs on top of a pretty polyglot architecture. The various components utilize node + Express, Scala + Akka, Java + Play, and of course Java and Objective-C for the mobile clients. Most of my personal development efforts have been on the web application, which is the part that runs on top of node.
As longtime fanatics of AWS, we've opted to run the web app on top of Elastic Beanstalk, and we use the built-in support for Nginx to serve up static files and protect the app servers from excessively large request bodies.
This has all been working swimmingly, and we've enjoyed sitting back and watching our server logs explode with new users that some recent foreign press seems to have generated for us (watch out, Hasselhoff, now we're big in Germany!).