tagline: From openSUSE
As of openSUSE 12.1 KDE 3 desktop is included as officially supported part of the distribution. Additional KDE 3 software can be installed from community-supported KDE:KDE3 repository.
If you are interested in (helping) maintaining the KDE3 repository for openSUSE, you are welcome to do so. Contact the KDE team in the #opensuse-kde channel on Freenode or on the email@example.com mailing list.
 Installing KDE 3
Easiest way to install KDE3 on any openSUSE version is to use 1-click install:
To manually install the KDE3 desktop, you will need to install kdebase3-session package - plus any of the package families that you would like (e.g. kdegames, kdegraphics etc). Under openSUSE 11.1 to 11.4 you would have to add KDE:KDE3 repository, under openSUSE 12.1 KDE3 is included in the main openSUSE repository. It is possible to use KDE3 packages when running a KDE4 desktop and kde4 packages when running a KDE3 desktop. So for example the music player Amarok version 1.4 (designed for KDE3 systems) will play fine when running the kde4 desktop and Amarok version 2 (designed for KDE4) will play fine when running the kde3 desktop.
To choose kdm3 as the default session manager one needs to write
DISPLAYMANAGER="kdm3" line to the file /etc/sysconfig/displaymanager (this can be done with the Yast module etc/sysconfig tool Editor as well).
OpenSUSE 11.4 may require you to manually enable the HAL daemon service through Yast2 in order to enable USB and DVD drives auto-mounting.
Since LibreOffice suite as packaged in openSUSE 11.4 does not support KDE3, it is recommended to use packages from the LibreOffice:Stable repository, where the support for KDE3 has been enabled. The libreoffice-kde package installed from that repository enables the use of KDE3 file picker dialogs by the LibreOffice components.
Under openSUSE 12.1 libreoffice-kde is available from the main repository.
 Mailing list
There is a dedicated list for KDE3 on openSUSE.