After the submission process for thousand of wallpapers on the Precise Pangolin flicker group, the Ubuntu design team finally select the final default wallpapers and the extra wallpapers which can be downloaded from the Precise repository.
All wallpapers looks pretty amazing with high resolution and its license under CC by SA. The default wallpaper for Ubuntu 12.04 LTS Precise Pangolin looks quite the same on the earlier releases Ubuntu Oneiric and Ubuntu Natty, however with each release they add some effect on it and additional colors. Check the default wallpaper down below.
By default, when Ubuntu 12.04 Precise Pangolin comes out in April 26th, 2012, the default wallpaper will be installed, for who currently running the development release of Pangolin, you can simply run the update manager it will install the new wallpapers package. Or you can install it by typing on terminal
sudo apt-get install ubuntu-wallpapers
Also for who want to install additional wallpapers for Ubuntu Precise, you might want to install the Ubuntu-wallpapers-extra package.
sudo apt-get install ubuntu-wallpapers-extra
Check this video preview for Ubuntu 12.04 Precise Pangolin with the default wallpapers and extra wallpapers as well. Also you will see a new neat thing about the OSD notify color, which it varies according to the wallpaper colors.