Ubuntu Guide posted a tutorial showing you how to install or upgrade the newly released KDE 4.9 in Ubuntu 12.04 Precise Pangolin

After six months of hard work, KDE announced its latest set of releases, KDE Plasma Workspaces, KDE Applications, and the KDE Platform version 4.9.0 on August 1, 2012. Provided many interesting and new features, quality improvements, and new updated applications.

  Install KDE 4.9 in Ubuntu 12.04 Precise