The release candidate is out from KDE for the upcoming 4.3.
Users of the Karmic development release can upgrade to the latest packages.
Note that these packages have a bug which causes X to die during the upgrade. The upgrade will continue and you can reboot when it is done.
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.