Kubuntu 14.10 beta 2 is out now for testing by early adopters. This release comes with the stable Plasma 4 we know and love. It also adds another flavour – Kubuntu Plasma 5 Tech Preview. Try Kubuntu Plasma 5 to see the future of desktop software but expect some more bugs as we iron out the integration.
Plasma 4 is our recommended stable offering and what you get from the default download, but is now in maintenance mode. It runs the software you are familiar with and will be getting updates and bugfixes but not new features from now on.
Plasma 5 a work in progress. The next generation of KDE Software is still a work in progress. You can test it and install it from the Kubuntu Plasma 5 image but beware it will remove your stable software.