Last week, Canonical released the first Ubuntu 10.04 beta, code named Lucid Lynx, which among other important changes, introduces Ambience, the new default theme that replaces the venerable Human which gave Ubuntu its characteristic brown looks.
Here’s a peek at Firefox 3.6 running on Lucid. It looks native which is not the same as looking good. I think the problem is the default Tango icons were not updated to match the new dark title and menu bars.
Also, Yahoo! is the default Firefox search engine in fresh Ubuntu installs like the shown below.