Evolve GTK3 theme has been updated to work with latest Ubuntu 12.04 and Gnome 3.4. The theme has been created by Satya who has designed another beautiful GTK3 theme Orion.
Install Evolve theme from PPA using the following commands:
sudo add-apt-repository ppa:satyajit-happy/themes
sudo apt-get update && sudo apt-get install evolve-gtk-theme