After upgrading to Ubuntu 13.04 i cannot run any more KDE programs under Ubuntu. I have both installed. Ubuntu and Kubuntu. I run Rkonq and K3B already lots of years under Ubuntu. But after the upgrade it is not possible any more. This is what i get starting Rekonq from a terminal: QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave. QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave. unnamed app(3756) kdemain: rekonq is already running!
I just got around to upgrading my work ubuntu machine, KDE environment would not run but it did complain about starting dbus. CTRL+ALT+F1 (or any console).
sudo apt-get install qdbus
The update uninstalled the 386 version and installed a new version. ALT+F7, login with KDE came up just fine after this.
ubuntu-sdk as described here: http://ubuntuforums.org/showthread.php?t=2130894&p=12581777#post12581777