This git repository helps you get up and running quickly w/ a node.js installation on OpenShift.
Create an account at http://www.openshift.com/
Create a nodejs-0.6 application (you can call your application whatever you want)
rhc app create mynodejs nodejs-0.6 --from-code=https://github.com/openshift/nodejs-example.git
That's it, you can now checkout your application at:
http://mynodejs-$yournamespace.rhcloud.com