With Source version 1.1, you'll be able to run Javascript in Node.js, on your iPhone and iPad!
I've been hard at work integrating Microsoft's ChakraCore fork of Node into Source for iOS. ChakraCore can run purely in interpretive mode, with no JIT, so it's now possible to run it on iOS.
Below, you can see a demo of npm and an express server running on-device.
This is all made possible by janeasystem's nodejs-mobile repo.