A while back there was a neat little styling script being passed around that tuned the Ubuntu Forums to match the new official designs a little more closely. While its not official and no where near a perfect solution, it does dramatically improve the appearance of the forums overall.
To use this, all you have to do is download and install the Stylesheet or UserJS file and configure it in your browser! I’m using the UserJS version, but you may prefer the other. Either way, enjoy!