Install GNOME 3 in Ubuntu 11.04
How to add GNOME 3 to Ubuntu
If you're one of the many people that is less than satisfied with Ubuntu's Unity desktop, don't worry. You can opt for GNOME 3 instead by installing it in Ubuntu 11.04.
Please note, however, that this tip will BREAK YOUR UNITY desktop and you can't go back once GNOME 3 is installed. So think carefully before doing this or try it first in VirtualBox with Ubuntu before messing with it on your actual Ubuntu desktop.
1. Add the GNOME 3 repository - Hit ALT+F2 and check the run in terminal option, then paste in the following commmand:
sudo add-apt-repository ppa:gnome3-team/gnome3
Enter your password when asked and hit okay (the terminal window will close automatically).
2. Hit the ALT+F2 combo again to open the run menu. Paste in the command below into run application box (make sure you check the "run in terminal" box):
sudo apt-get dist-upgrade
When asked if you want to upgrade your packages, type Y and then hit enter.
3. Install GNOME 3 - Hit ALT+F2 and check the "run in terminal"
box. Then paste the command below:
sudo apt-get install gnome-shell
Enter your password, hit enter and then type Y when asked if you want to install gnome-shell. GNOME 3 will install on your system.
Enjoy your new GNOME 3 desktop environment.
How to Install GNOME 3 on Ubuntu 11.04 | Softpedia