KDE 4 has been released. I’ve received couple of questions about installing KDE 4 under Ubuntu Linux 7.10. KDE 4 Packages are available for Ubuntu Linux version 7.10 (Gutsy) and from development Ubuntu Linux Hardy version. They install to /usr/lib/kde4 and can be installed alongside your existing KDE 3. However these packages are not compatible with KDE 4 beta packages. Following simple step will help you install KDE 4.
How do I install KDE 4 under Ubuntu Linux?
First you need to update Ubuntu package source file.

Step # 1: Update Source File
Open a terminal
Open /etc/apt/sources.list file using a text editor such as vi or gedit, enter:
$ sudo vi /etc/apt/sources.list
OR
$ sudo gedit /etc/apt/sources.list
Append following line:
deb http://ppa.launchpad.net/kubuntu-members-kde4/ubuntu gutsy main
Close and save the file. Type the following command to update package list:
$ sudo apt-get update
GUI tool to update software source
Alternatively, you can use GUI tool by visiting System > Administration > Software Sources > Third Party Software > Add > Enter url ‘deb http://ppa.launchpad.net/kubuntu-members-kde4/ubuntu gutsy main‘ > Add Source > Update > Close
(Fig. 01: Update Software Source for KDE 4)
Step # 2: Install KDE 4 desktop
To install kde 4, enter:
$ sudo apt-get install kde4-core
You’ll get a warning when installing kde 4, just force to install the same without verification:
WARNING: The following packages cannot be authenticated!
Install these packages without verification [y/N]? y
Output:
Reading package lists... Done Building dependency tree Reading state information... Done The following extra packages will be installed: dbus-x11 dolphin-kde4 kappfinder-kde4 kde-icons-oxygen kde4libs-bin kdebase-bin-kde4 kdebase-data-kde4 kdebase-kde4 kdebase-runtime kdebase-runtime-bin-kde4 kdebase-runtime-data kdebase-runtime-data-common kdebase-workspace kdebase-workspace-bin kdebase-workspace-data kdelibs5 kdelibs5-data kdepasswd-kde4 kdepimlibs-data kdepimlibs5 kfind-kde4 klipper-kde4 konqueror-kde4 konqueror-nsplugins-kde4 konsole-kde4 ksysguard-kde4 ksysguardd-kde4 kwin-kde4 kwrite-kde4 libcapseo0 libcaptury0 libclucene0 libexiv2-0 libgpgme11 libkonq5 libkonq5-templates libphonon4 libplasma1 libpth20 libqimageblitz4 libraptor1 librasqal0 librdf0 libsoprano4 libstreamanalyzer0 libstreams0 libstrigiqtdbusclient0 systemsettings-kde4 Suggested packages: kdebase kde-i18n sword-frontend gpgsm Recommended packages: exiv2 raptor-utils redland-utils The following NEW packages will be installed: dbus-x11 dolphin-kde4 kappfinder-kde4 kde-icons-oxygen kde4-core kde4libs-bin kdebase-bin-kde4 kdebase-data-kde4 kdebase-kde4 kdebase-runtime kdebase-runtime-bin-kde4 kdebase-runtime-data kdebase-runtime-data-common kdebase-workspace kdebase-workspace-bin kdebase-workspace-data kdelibs5 kdelibs5-data kdepasswd-kde4 kdepimlibs-data kdepimlibs5 kfind-kde4 klipper-kde4 konqueror-kde4 konqueror-nsplugins-kde4 konsole-kde4 ksysguard-kde4 ksysguardd-kde4 kwin-kde4 kwrite-kde4 libcapseo0 libcaptury0 libclucene0 libexiv2-0 libgpgme11 libkonq5 libkonq5-templates libphonon4 libplasma1 libpth20 libqimageblitz4 libraptor1 librasqal0 librdf0 libsoprano4 libstreamanalyzer0 libstreams0 libstrigiqtdbusclient0 systemsettings-kde4 0 upgraded, 49 newly installed, 0 to remove and 2 not upgraded. Need to get 105MB of archives. After unpacking 204MB of additional disk space will be used. Do you want to continue [Y/n]? y WARNING: The following packages cannot be authenticated! libphonon4 libstreams0 libstreamanalyzer0 kdelibs5-data kde4libs-bin kdelibs5 libstrigiqtdbusclient0 libkonq5-templates libkonq5 dolphin-kde4 kappfinder-kde4 kdebase-data-kde4 kdebase-bin-kde4 kdepasswd-kde4 kfind-kde4 konqueror-nsplugins-kde4 konqueror-kde4 konsole-kde4 kwrite-kde4 kdebase-kde4 kdebase-workspace-data libplasma1 ksysguardd-kde4 ksysguard-kde4 kdebase-workspace-bin klipper-kde4 kwin-kde4 systemsettings-kde4 kdebase-workspace kdepimlibs-data kdepimlibs5 kde4-core... Install these packages without verification [y/N]? y Get:1 http://ppa.launchpad.net gutsy/main libphonon4 4:4.0.0-0ubuntu2~gutsy1~ppa1 [164kB] Get:2 http://archive.ubuntu.com gutsy-backports/universe kde-icons-oxygen 4:4.0.0-0ubuntu1~gutsy1 [45.4MB] Get:3 http://in.archive.ubuntu.com gutsy/main dbus-x11 1.1.1-3ubuntu4 [34.8kB] ................ ... ......... Setting up systemsettings-kde4 (4:4.0.0-0ubuntu7~gutsy1~ppa1) ... Setting up kdebase-workspace (4:4.0.0-0ubuntu7~gutsy1~ppa1) ... Setting up kde4-core (3.3~gutsy1~ppa1) ... Processing triggers for libc6 ... ldconfig deferred processing now taking place
Note: It may take some time to install kde 4. You also need to disable compiz 3d desktop effect support.
References:
=> Kubuntu Project – Be Free with KDE 4.0