I don't know if these are know problems, or if KDE4 is to the point of filing bugzillas but I noticed two things after updating to KDE4 ( rawhide today)
 
1) /bin/dbus-daemon has selinux issues.  Running in enforcing mode yields "permission denied".  permissive mode works fine.
2) after the splash screen, I get no desktop.
 
Mark Bidewell