New Wave is a truly awesome Gnome theme available in Ubuntu's community-themes package for quite a few releases.
A new version of New Wave has just been released: New Wave 0.90 beta 1 which you can download from HERE.
To install it, firstly you'll have to remove the existing New Wave theme (if any):
rm -r New\ Wave
Then to install New Wave 0.90 Beta 1, right click on your Desktop, select "Change Desktop Background", select the "Themes" tab and then simply drag and drop the downloaded New Wave 0.90 beta 1 archive (.tar.gz) onto the "Themes" tab.