WELCOME TO ARCHLINUX KDE WIKI
Info from Package Maintainer tpowa:
Please don't change the docu without notifying me, please send me a short mail about your changes. This docu is based on kde 3.4.1!
Please change to console mode before you upgrade KDE, else your icons may get lost in your panel. Update from kde3.4 Beta1 to kde 3.4: please deinstall kdebase-config, it's replaced by kde-common. If you get trouble with menus not appearing please deinstall kde first and then reinstall with new packages.
Where to get kde 3.4:
It is available in extra repository. Thanks for your feedback. Enjoy the new kde release. Have fun with the new features and please report problems.
Forum link for dicussion: 
If you still have problems after the upgrade, consider your .kde/ could have configs inside that are not compatible with new kde 3.4. Please move the files to a save place and start with a new .kde/ dir in your home. If you have installed extensions or additional software for kde(not from our repos), it could be that they break kde 3.4. Please rebuild them against new kde 3.4 or deinstall them. devices:/ kioslave is depracted, to get new layout: please delete your /home/$user/.kde/share/apps/konqsidebartng/ kde 3.4 provides new feature of kcompmgr (composite extension of xorg), if you enable it, it may crash your X-Server, you have been warned. storage applet can cause some extensive logging, be aware of this problem and check your /var/log/ on size. It happens only if you do a safely remove,let the usb device connected and your usb device must be some kind of broken. At the moment we have some problems getting kdebase to new hal/dbus, we are working on solving this issue immediatly. (this is fixed in kdebase-3.4.1-4.pkg.tar.gz) KSim panel applet crashes from time to time. NFS shares are not shown on desktop, storage applet and not in media:/
If you want to have access to Windows services 'pacman -S samba'.
If you want to have Java support: 'pacman -S j2re'
If you want to have printing support: 'pacman -S <enteryourfavouriteprintingsystemhere>' it is preconfigured for cups in kcontrol
If you experience problems with the default fonts setting, e.g. that special characters for your language do not appear, try to set the fonts in 'kcontrol to a font which supports that characters
KDM Xserver file:
KDM does not use the /opt/kde/share/config/kdm/Xserver file any more, everything is in /opt/kde/share/config/kdm/kdmrc now, check file kdmrc.default to see all options (e.g. -dpi 100).
Please add 'dbus' 'hal' to rc.conf daemon's list for full media:/ kioslave experience.
To enable gpg-agent and/or ssh-agent in KDE sessions, edit '/opt/kde/env/agent-startup.sh' and '/opt/kde/shutdown/agent-shutdown.sh'.
Kdebindings has been built with support for Java and GTK. If you want to use these features use the following pacman commands: 'pacman -S j2sdk' 'pacman -S gtk'
Kdesdk has been built with support for Subversion. If you want to use this feature use the following pacman command: 'pacman -S subversion'
If you think you found a bug, please verify that this bug also happens with a new created user, with a clean setup, some bugs happen due to misconfiguration in config files. If the new user doesn't show the bug, try to move the config files of your existing user. kde config files are usually located at: /home/$user/.kde/share/config or if app specific at: /home/$user/.kde/share/apps
About KDE package splitting:
The problem is that KDE has to change their packages in providing. pacman is not made for making multiple packages out of one tarball. And don't forget it has to be maintainable. (not too time consuming!) I'm not planning to split the packages.
About why do packages appear before official release:
Packagers get the tarballs a week earlier then official release, to have time to build and fix last showstoppers while building. --> the packages are most time the final ones when they appear in arch repos, even before offical release.