Hey Beer,

The reason that feature, hiding navigation bar (Nav Bar), is not in FF is security related ---> http://www.webdeveloper.com/forum/sh...24&postcount=6

There is a FF add-on to hide the nav bar by pressing the F2 key ---> https://addons.mozilla.org/en-US/fir...ar/?src=search
Hide all GUI bars with a customizable key shortcut (default is Ctrl-Shift-A) ---> https://addons.mozilla.org/en-US/fir...rs/?src=search

For FF 4 there is an extension to mimic Google's feature - Article (Link) - Download (Link)