It seems like what this project is about (driving phantomjs over network calls) is exactly what was build into version 1.8 of phantomjs.
Dont you think it would be better if you only write the nodejs part of the driver and used the webdriver code already in phantomjs? Code you dont write is the best code!
It seems like there are implementations available from selenium in Ruby, Java, PHP, Python and C#.
There is even a node implementation of the webdriver client http://code.google.com/p/selenium/wiki/WebDriverJs?
I'm switching to Ruby to use/drive phantomjs. But goodluck with your project!
Some links to the project..
http://phantomjs.org/release-1.8.html
https://github.com/detro/ghostdriver
http://code.google.com/p/phantomjs/issues/detail?id=49