As you probably know, Docky will not be a part of Gnome Do anymore. There was a PPA to install the development version of Docky in Ubuntu, but the Docky package has been removed. Fortunately, there now is an official Docky development PPA.

To add the Docky development PPA to the Ubuntu Karmic (also works for Ubuntu Lucid Lynx) software sources, run the following command in a terminal:

sudo add-apt-repository ppa:docky-core/ppa

Then install it, if you haven't already:

sudo apt-get update && sudo apt-get install docky

or upgrade:

sudo apt-get update && sudo apt-get upgrade