I’ve just released WebPageTest API Wrapper for NodeJS. It wraps WPT API from any instance (public or private) and make it available as Node module, command line and as a RESTful API proxy.
Check it out at http://marcelduran.com/webpagetest-api
There’s a live API Console demo at http://marcelduran.com/webpagetest-api/console
Looking forward for your feedback and contributions.