Many people raised concerns that they have to decide between ubuntu and gnome not between gnome shell and unity shell within ubuntu. Do not worry people as a new Ubuntu Remix has been started. The project plans to release future versions of Ubuntu with vanilla Gnome instead of Unity. Ubuntu Gnome Remix project already have a launchpad page and a website setup. Find details on their respective pages and if you are interested and if you can please join the team and lend a helping hand.
Ubuntu Gnome Remix (UGR) is a remix of Ubuntu to include a full version of gnome. Mark Shuttleworth has stated that versions of Ubuntu from 11.10 and on will not ship the classic Gnome interface, opting instead for the Unity interface. This project is based almost entirely on regular Ubuntu, with just a few changes to the interface.
This project is in the VERY early stages. The Natty (11.04) release will include Gnome 3. Fallback to old-style Gnome may be available at a later date. This project is remixed by the team at http://ugr.teampr0xy.net. It has not yet been approved and is not sponsored by Ubuntu, Gnome, or Canonical in any way. It is not for profit and currently has no commercial objectives.
Installing
1) Obtain a clean, fresh installation of the latest 11.04 Natty Narwhal beta. Perform all applicable updates.
2) Configure the system to NOT login automatically. This is needed so that you can choose what kind of session you want. If you do not do this, you will still be stuck with unity. This can be changed under system>preferences>login screen.
3) Add the UGR Repositories:
$ sudo add-apt-repository ppa:ubuntugnometeam/gnome3
$ sudo add-apt-repository ppa:ubuntugnometeam/ppa-gen
$ sudo apt-get update
4) Install UGR
$ sudo apt-get dist-upgrade
$ sudo apt-get install ugr-desktop-g3 gnome-shell
$ sudo apt-get upgrade
5) Reboot. You should see “GNOME 3″ and “GNOME shell” as a session option in the login screen.
Issues
# Dependency issues and conflicts with gnome-themes-standard and gnome-accessibility-themes
# Ubuntu may try to get rid of ugr-desktop-g3 and reinstall ubuntu-desktop
# Many parts of GNOME crash constantly
This is an initial demonstration, Not intended for production machines.

