If it's possible, how can I upgrade KDE 4.9 in Kubuntu 11.10 ?
I added the backports but nothing new.
Kubuntu 11.10 support
The Kubuntu 11.10 will get bug fixes and security patches for the KDE 4.7.4: http://www.kubuntuforums.net/showthread.php?59191-Will-there-be-KDE-4-8-4-updates-or-backports-for-oneiric
The Kubuntu 11.10 will be supported to the 2013-04: http://en.wikipedia.org/wiki/Kubuntu
Kubuntu and the KDE 4.9
The KDE SC 4.9.0 is available for the Kubuntu 12.10 (under development) and the Kubuntu 12.04: http://www.kubuntu.org/news/kde-sc-4.9
Packages for the release of KDE's Plasma and Applications 4.9 are available for Kubuntu 12.04. You can get it from the Kubuntu Backports PPA. They are also in our development release...