The Kubuntu Team announces the availability of Plasma 5.6.4 on Kubuntu 16.04 though our Backports PPA.
Plasma 5.6.4 Announcement:
How to get the update (in the commandline):
1. sudo apt-add-repository ppa:kubuntu-ppa/backports
2. sudo apt update
3. sudo apt full-upgrade -y
Here is a great video demoing the some of the new features in this release: