Looks like it's using a variant of a technique I demonstrated a while back: http://joshduck.com/blog/2010/01/29/abusing-the-cache-tracking-users-without-cookies

Looks like it's using a variant of a technique I demonstrated a while back: http://joshduck.com/blog/2010/01/29/abusing-the-cache-tracking-users-without-cookies/ http://joshduck.com/blog/2010/01/29/abusing-the-cache-tracki...