Packages for the release of KDE Applications 15.04 are available for Kubuntu 15.04. You can get it from the Kubuntu Backports PPA.
Packages for the release of KDE's desktop suite Plasma 5.3 beta are available for Kubuntu Vivid. You can get it from the Kubuntu Beta PPA.
The second Beta of Vivid (to become 15.04) has now been released!
The Beta-2 images can be downloaded from: http://cdimage.ubuntu.com/kubuntu/releases/vivid/beta-2/
More information on Kubuntu Beta-2 can be found here: https://wiki.kubuntu.org/VividVervet/Beta2/Kubuntu
Packages for the release of KDE's document suite Calligra 2.9 are available for Kubuntu 14.10. You can get it from the Kubuntu Backports PPA. They are also in our development version Vivid.
The second update to our LTS release 14.04 is out now. This contains all the bug fixes added to 14.04 since its first release in April. Users of 14.04 can run the normal update procedure to get these bug fixes.
See the 14.04.2 release announcement.