As you already know, Linux Mint 15 Olivia has just been released, a few days ago. Because it comes, by default, only with Mate and Cinnamon, users may want to change its desktop environment.
In this article I will show you how to install Gnome Shell 3.8 on Linux Mint 15 Olivia.
Warning: Do not do this on the Cinnamon edition because it may break your operating system for good.
$ sudo add-apt-repository ppa:gnome3-team/gnome3
$ sudo apt-get update
$ sudo apt-get install gnome-shell gnome-shell-extensions gnome-tweak-tool
Reboot and login to the Gnome Shell.