Gnome 3 has just released and the gnome3-team ppa only provides packages for Ubuntu 11.04 Natty. It is said that Gnome 3 PPA breaks the original Unity desktop environment so it’s recommended to try Gnome 3 on a virtual guest Ubuntu.

To install Gnome 3 in Ubuntu 11.04 Natty:

sudo add-apt-repository ppa:gnome3-team/gnome3
sudo apt-get update
sudo apt-get dist-upgrade
sudo apt-get install gnome-shell

For Ubuntu 10.10, there’s only Gnome 3 stack for testing and builds on launchpad.net and it’s not recommended to update.

sudo add-apt-repository ppa:Ubuntu-desktop/gnome3-builds
sudo apt-get update
sudo apt-get install gnome-shell