I guess everyone already knows that OpenOffice.org 3.0.0 will not be available (sad, I know) for the Intrepid Ibex (Ubuntu 8.10), because the developers did not have enough time to test it, and they will introduce it later this year. Therefore, Ubuntu 8.10 ships with OpenOffice.org 2.4.1 and, if you want to use the new and improved version, then this guide is for you! However, we will not do a fresh install of the OpenOffice suite, as we will instead only upgrade the current version in Ubuntu Intrepid.
OK, so... first thing, you must add the OpenOffice.org 3.0 repositories, then upgrade the installed packages. Follow the steps below!
STEP 1 - Add the OpenOffice.org 3 repositoriesGo to System -> Administration -> Software Sources...

Go to the second tab, "Third-Party Software," click on the "Add" button, and paste the line below...
deb http://ppa.launchpad.net/openoffice-pkgs/ubuntu intrepid main
Now, click the “Close” button, then the “Reload” one and wait for the application to close!
STEP 2 - Update OpenOffice to version 3.0.0
When the Software Sources window will close itself, the update icon will appear in the system tray...

Click on it and update your system! That's all, folks! Your open source office suite will be up-to-date from now on.