Howtoforge posted a tutorial about installing GNOME 3 on Ubuntu 11.10

This tutorial shows you how you can install the GNOME 3 desktop on Ubuntu 11.10 with the shell extensions that are used in the Linux Mint 12 release (Lisa) (these shell extensions are called Mint GNOME Shell Extensions - mgse). These shell extensions give GNOME 3 the look and feel of GNOME 2. For those who prefer GNOME 2 this tutorial shows how to install Mate from the Linux Mint repositories on Ubuntu 11.10. Mate is a GNOME 2 fork.

  Install GNOME 3 (With Mint GNOME Shell Extensions) Or Mate On Ubuntu 11.10 (Oneiric Ocelot)