Cairo-Dock is an very popular animated application launch bar in Ubuntu,comparable to the dock in Mac OS X or Rocket Dock.Unfortunately the Cairo-Dock’s domain has changed,the new website is glx-dock.org.
In Ubuntu Karmic and older,we need change the repository, simply replace ‘cairo-dock.org’ by ‘glx-dock.org’ to keep update.

If you want to test the latest version, updated every weeks.Keep reading:
Open terminal from Applications->Accessories menu,then copy and paste following 5 commands:

sudo -v
echo "deb http://ppa.launchpad.net/cairo-dock-team/weekly/ubuntu $(lsb_release -sc) main ## Cairo-Dock-PPA-Weekly" | sudo tee -a /etc/apt/sources.list
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E80D6BF5
sudo apt-get update
sudo apt-get install cairo-dock

glx_dock

To learn more about Cairo-Dock:
MainPage:http://www.glx-dock.org/
Wiki:http://www.glx-dock.org/ww_page.php?p=Accueil〈=en
Forum:http://www.glx-dock.org/bg_forumlist.php