I have not seen it specifically spelled out anywhere that I can't use New Relic with node.js, just not much mention of it being done. Thanks for any feedback!
New Relic has Node.js support on our radar, whether hosted on Heroku or otherwise. The support is not ready for prime time yet. We will ensure to make lots of noise when everything is ready to go.
The Newrelic Agent for Node.JS is currently in beta, official support should be announced soon. You can get the agent here: