While the LibreOffice website does offer .deb files for download, it's usually better to use a PPA for this since you'll always get the latest LibreOffice version automatically, like any other update. Further more, the LibreOffice packages in this official LibreOffice Ubuntu PPA are backported from Natty so they come with all the patches/optimizations applied to LibreOffice for Ubuntu.
sudo apt-get remove openoffice*
sudo add-apt-repository ppa:libreoffice/ppa
sudo apt-get update
sudo apt-get install libreoffice
The LibreOffice PPA currently provides LibreOffice 3.3.1 for Ubuntu 10.04, 10.10 and 11.04.
To integrate Libreoffice with your desktop environment, also install the following package:
- GNOME:
sudo apt-get install libreoffice-gnome
- KDE:
sudo apt-get install libreoffice-kde
When removing OpenOffice, the spellchecker and the language support package are also removed. Get these packages back to use with LibreOffice by installing the following package (thanks to Paul for the tip!):
sudo apt-get install language-support-en
You can replace "-en" with your language in the above command.