title: How is pjax working?
body: <p>I just discovered <a href="http://pjax.heroku.com/" rel="noreferrer">pjax</a> and I find it completly awesome. If I understand it correctly, it's AJAX, but without its problems (fully degradable, the URL and the title of the page is changing when using it, compatible with search bots...).</p>
  
  <p>But I am very curious as how it's working ? How can we change the URL in the browser, without the page to change... I read somewhere you need Firefox 4, is that a new "web" feature then ?</p>