UPDATE:In Ubuntu 9.04 you can get this dock via Synaptic.
*First open terminal located in Applications>accessories>terminal
Next type the following:
wget -q http://repository.cairo-dock.org/ubuntu/cairo-dock.gpg -O- | sudo apt-key add -
Next edit your sources list by typing:
sudo gedit /etc/apt/sources.list
When the file opens scroll to the very bottom and add this line:
deb http://repository.cairo-dock.org/ubuntu hardy cairo-dock
save the file and close it.
Next type in:
sudo apt-get updatethen
sudo apt-get install cairo-dock cairo-dock-plug-ins
the dock should now download and install and is located under Applications>system
Hope this helps thanks for reading. If you have questions or need help please leave a comment.