Q:

Automated Web UI testing in nodejs

Are there any automated web testing libraries for nodejs, preferably headless?

A:

Zombie is a headless full-stack testing framework for Node.js.
Edit: To add to that, there's a full list of testing modules on the Node.js GitHub wiki.

A:

You should also check out PhantomJS and CasperJS. Together, it's a testing framework in pure JavaScript with a headless WebKit browser. Works in Linux, OSX and Windows.

A:

Selenium now has JavaScript bindings for Node.js.  You can use a headless driver along with the Selenium bindings.  (Check out ghostdriver)
Basically all you have to do is install node, setup your driver and then get your selenium module with npm selenium-webdriver.
I have some more detailed instructions and screenshots in my tutorial, here.

