KDE 4.3 Beta 1 is now available in the Kubuntu Karmic repositories.
Packages for Jaunty are available in the Kubuntu Experimental repository. To install these, add this line to your software sources.
deb http://ppa.launchpad.net/kubuntu-ppa/experimental/ubuntu jaunty main
Then refresh and do a full upgrade.
KOffice 2 has been released and packages are available for Kubuntu.
Users of our development release, Karmic, can install koffice-kde4.
If you are using the current 9.04 release add the backports Unsupported updates repository and install koffice-kde4.