Satya has updated his his Gnome Shell theme 'Shine' making it compatible with latest Gnome 3.4 and Ubuntu 12.04.
Shine is a light theme that nicely blends transparency and usability, with smooth transition effects between different elements.
Use User Theme Extension and Gnome Tweak Tool to switch Gnome Shell themes. Gnome Tweak Tool can be installed from Ubuntu Software Center. User Theme extension can be installed by running commands below:
sudo add-apt-repository ppa:satyajit-happy/themes
sudo apt-get update
sudo apt-get install gnome-shell-extensions