Kubtuntu 10.10 is shipped with KDE 4.5.1, here is how to update to the latest release version 4.5.3 using the Kubuntu’s PPA.
Add the repository
sudo apt-add-repository ppa:kubuntu-ppa
Update the repositories
sudo apt-get update
Upgrade
sudo apt-get dist-upgrade
reboot
IMPORTANT: After my first reboot I was able to log in however once I entered my username and password I was then presented with a black screen. To fix this I hit ATL+CTRL+F2 to get to a bash shell. Once logged in type sudo apt-get install plasma-desktop then rebooted. To eliminate this issue before the first reboot you might be able to do the distro-update and then the apt-get install plasma-desktop then reboot. I am not able to test this theory since I have already updated my system.
Note: Doing just a regular apt-get upgrade will not get all of the necessary packages and looks like it want to remove a bunch of KDE packages.