Unfortunately, even though Intrepid Ibex (Ubuntu 8.10) shipped quite a bit after the release of OpenOffice 3.0, the developers hadn’t quite finished testing Intrepid with the latest version. As a result, Ubuntu 8.10 ships with version 2.4 of the popular, free office suite.
The latest version of OpenOffice adds many new features, including an enhanced user interface, compatibility with Microsoft Office 2007’s XML formats (docx, pptx), and improved speed and reliability all round.
Softpedia outlines the proper way to update your OpenOffice suite. You just have to add the following to your list of software sources: deb http://ppa.launchpad.net/openoffice-pkgs/ubuntu intrepid main and then update via the Update Manager:
[How to Install OpenOffice.org 3.0 on Ubuntu 8.10 – Step by step tutorial with screenshots! – Softpedia]