Hello Linux Geeksters. As you may know, GNOME Shell 3.12 and GTK +3.12 have been added to the proposed repositories of Ubuntu 14.10 Utopic Unicorn. Most likely, they will be soon added to the default repositories so the users will be able to have the latest versions of the Gnome applications, on their system.
For now, only GNOME Shell and GTK+ are updated to version 3.12, while the other apps are still the ones from GNOME 3.10 or older.
As a reminder, Ubuntu GNOME 14.10 will be using GNOME 3.12, due to the fact that GNOME 3.14 will be released on September and Ubuntu 14.10 is scheduled for October, so there is no time to test and optimize the latest GNOME iteration until the release of the next Ubuntu system.
But if you are using one of the Ubuntu 14.10 daily build images, you can install and test GNOME 3.14 (which is still under development), via PPA.
While both Ubuntu 14.10 and GNOME 3.14 are under development, it is advised not to install the latest GNOME desktop environment on your main system, because you may break it.
All you have to do to install GNOME 3.14 on Ubuntu 14.10 is to add the needed PPAs to your system:
$ sudo apt-add-repository ppa:gnome3-team/gnome3
$ sudo apt-add-repository ppa:gnome3-team/gnome3-staging
$ sudo apt-add-repository ppa:ricotz/testing
Update the local repository index:
$ sudo apt-get update
And perform a normal system upgrade:
$ sudo apt-get dist-upgrade
$ sudo apt-get install gnome-shell
Optional, to revert the changes and switch back to the Gnome version from the official Ubuntu 14.10 repositories, install ppa-purge and “purge” the recently added Gnome PPAs:
$ sudo apt-get install ppa-purge
$ sudo ppa-purge ppa:ricotz/testing
$ sudo ppa-purge ppa:gnome3-team/gnome3-staging
$ sudo ppa-purge ppa:gnome3-team/gnome3