I don't think so; the problem with Firefox as far as I am concerned is that it used to take up far too much space at the top of the screen - not a good strategy when most screens have more horizontal than vertical space. It still isn't as stripped down as Konqueror, which only has three rows compared with Firefox's four, but it is an improvement from my point of view.
Using Ubuntu 10.10 with the Firefox 4 PPA (http://ppa.launchpad.net/mozillateam/fi ... ble/ubuntu) and there is a major difference to Firefox 4 on Windows 7. The title bar is still displayed, realistically just to display the 3 buttons in the top left (Close/Minimise/Maximise). This taking up extra room that could be used to display web page content.