KDE 4.3 RC 3 has been released.
Users of our latest development release, Karmic, can upgrade to the latest packages.
Users of our stable 9.04 release can install it from the Kubuntu Backports PPA.
deb http://ppa.launchpad.net/kubuntu-ppa/backports/ubuntu jaunty main
It is strongly recommended that you verify the integrity of these packages by installing the archive's GPG key. You may do this by following the instructions on this page.
Then refresh and do a full upgrade.