Kiran Prasad (running mobile development at LinkedIn), talks about their approach to building hybrid applications:
- Reuse of HTML5 code across all three applications (mobile web, iOS and Android)
- Client framework : Backbone + Zepto + Underscore + Handlebars + Stylus
- Server-side : node + socket.io (WebSockets) + redis + mongo
On the specific node.js topic, see : http://venturebeat.com/2011/08/16/linkedin-node/