This theme is working on Gnome 3.6 also. A modifled Adwaita Cupertino theme is provided with this theme.
Mountain Shell Includes:
– Minimalistic, simple, beautiful, elegant look
– New pane
– New switch ON/OF buttons
– OS X Mountain Lion Overview/Workspaces look
– Simple, fast, responsive, beautiful menu selection
– New arrow workspace switch
– New calendar current day selection
& some more new good looking elements.
to install this theme in ubuntu or fedora just extract the downloaded folder into /usr/share/themes/ or into ~/.themes/
Nice theme to change the look of the desktop to Mountain Lion Mac OSX .