Many prefer to use Gnome 3.2 on Ubuntu because they don't like Unity. There are 4 methods to install it on Ubuntu 11.10 Oneiric Ocelot with the included repositories.
Open the terminal and type the command below:
If it doesn't work, try method 2.
Still at the terminal:
In the Search field look for gnome-shell and install it.
If it still doesn't work out
At the terminal:
After installation, you need to login to the system by choosing the optionGNOME in the gear cone next to the password field.
Method 4: Well, that's enough line of text, the truth is that if you go to the new Ubuntu Software Center and look for Gnome-shell and install this package or the graphic environment will be installed.
Restart the session and change gear to GNOME.
Have a good time!