I commited today two fixes to the KDE SVN to make KDBus usable again on DBus method calls:
- fixed show the input widgets for input/output method parameters, show in the 'Output:' section only the output and not again also the input parameter widgets 
- fixed handling of boolean method parameters, now you should be able to call e.g. SetPowerSave(bool) on the org.freedesktop.Hal.Device.SystemPowerManagement interface again without errors 
Updated RPM packages are already available for openSUSE 10.2 - openSUSE Factory and SUSE Linux Enterprise (Desktop) 10 as always in my openSUSE Build Service project.