Simple How to Install KDE 4 on Ubuntu . . .

1. Open your sources.list
   $ sudo gedit /etc/apt/sources.list
2. Add new repo line
   deb http://ppa.launchpad.net/kubuntu-members-kde4/ubuntu gutsy main
3. Update your systems
   $ sudo apt-get update
4. Install kde4 system
   $ sudo apt-get install kdebase-workspace kdebase-kde4 kdebase-runtime kde4-core kde4
5. And now, KDE 4 sessions should appear in your login manager.