Nearing final release of Ubuntu 12.04, Canonical releases an update of the pack "Ubuntu Wallpapers" that reaches the version 0.34.0 allowing the installation of all Ubuntu wallpapers from Karmic until you get to Oneiric, and of course Precise, directly in Ubuntu 12.04!
All the wallpapers of Ubuntu in Precise Pargolin
To install all wallpapers in Precise Pangolin, you must type the following command from a terminal:
sudo apt-get install ubuntu-wallpapers-karmic ubuntu-wallpapers-lucid ubuntu-wallpapers-maverick ubuntu-wallpapers-natty ubuntu-wallpapers-oneiric ubuntu-wallpapers-precise
It is also possible to install only the wallpaper of a particular distribution with the command:
ubuntu-wallpapers-name of distribution
Example: ubuntu-wallpapers-oneric to get the wallpaper of Ubuntu 11.10
All the wallpapers of Ubuntu in Oneric Ocelot and earlier
To install all of the wallpapers of the Ubuntu distributions in Oneric Ocelot or earlier ,You must download the the following pack and enjoy the beauty of Ubuntu Wallpapers.