An interesting update in Firefox 4.0b7 now displays url in the address bar when you move your mouse pointer over a link in any webpage.The address bar changes a bit with a angular devider between the already existing url of the current web page and the one you mouse hover.
Another thing to notice is the URL is shortened to include the last part of any web url when you re size the Firefox Window. Sad part is you cannot define the length of any of them.
As of now I am exploring more updates which I did not see in the Release notes. Did you catch any change ?