Since updating my Ubuntu to 10.04 I have been a bit miffed that Nautilus seems to have lost the normal address window (I think the correct name is the location bar)
Now I have found out the short-cut. You can switch to a text bar by using Ctrl + L. To go back to a button style bar, just press the escape key.
You can also go directly to the Nautilus bar in text-mode by pressing the “/” key and then typing the location.