I'm intrigued, what would be the most common use cases for using node.js in > the phone?
Your imagination is the limit :) node can be used in any situation where the phone serves its local data (eg for desktop sync, peer-to-peer sharing,
etc).
This port is being used as the basis for the Webinos implementation on Android (see here: https://developer.webinos.org/) among other things.
Don't forget also that Android isn't just phones these days.