Packages for the release of KDE SC 4.10.3 are available for Kubuntu 13.04, 12.10 and 12.04. You can get them from the Kubuntu Updates PPA for 13.04 and from the Backports PPA for 12.10 and 12.04.
Bugs in the packaging should be reported to kubuntu-ppa on Launchpad. Bugs in the software to KDE.
To update, use the Software Repository Guide to add the following repository to your software sources list:
13.04:
ppa:kubuntu-ppa/ppa
12.10, 12.04:
ppa:kubuntu-ppa/backports
Or, from your konsole:
sudo apt-add-repository ppa:kubuntu-ppa/ppa
sudo apt-add-repository ppa:kubuntu-ppa/backports
Thanks to Philip and Rohan for their work on these packages