This is a small KDED daemon that allows switching one taskbar item to the left/right by pressing a shortcut (Meta+Left/Right by default, configurable in Systemsettings->Keyboard&Mouse->Global Shortcuts->KDE daemon).
Note that the module is loaded during KDE startup, so after installation KDE restart or 'qdbus org.kde.kded /kded loadModule taskbarswitch' is needed to activate it.
This feature was available in Kicker in KDE3 and has not yet been implemented in Plasma. This was written during the KDE4.3 feature freeze, and Plasma should now accept a patch implementing this. If you want, feel free to try to write the patch for Plasma, I possibly will not get that soon to doing it.
Packages for openSUSE, SLED, Fedora, Kubuntu and Mandriva are available in the openSUSE build service repository home:llunak:kde (see http://en.opensuse.org/KDE/Build_Service for installation instructions).