Headless: Xvfb on Linux. (Virtual Framebuffer, let's you run apps that require a GUI) You can use one of the many options that include Webkit (like phantom.js, the capybara-webkit gem, or Selenium if you want a real browser like Firefox to do the work)
well, it wasn't due to anything in phantomjs actually -- it was because qt introduced project lighthouse & their qt platform abstraction. project lighthouse was a fork that got integrated into qt 4.8 that phantomjs includes. (you can see the entire qt source tree if you git-clone phantomjs)
