Mint-Z is default Gnome Shell Theme that use in Linux Mint 12 'Lisa'. As other Linux distro does, Linux Mint 12 come with special features/appearance that show their identity, therefore Mint-Z is believed to be the identity of Lisa 'Linux Mint 12'.
Mint-Z is theme that based on Zukitwo but honestly it's not much different from Zukitwo, i notice only a few changes happen including replacing the Activities button with Linux Mint logo, changing the Shell colours, and fixing the GTK3 menu scroll buttons. Although it designed for Linux Mint you can install it in Ubuntu.
Install Mint-Z Theme in Ubuntu
Before it's start, download Mint-Z Improved through following links :
|Mint-Z Dash Screenshot|
|Mint-Z Desktop Screenshot|