In my case all is working well. I have Kubuntu 13.04_x86_64. Cmake scripts related to Qt5 are in /usr/lib/x86_64-linux-gnu/cmake directory. If you dont have them here something must go wrong with your installation. I have Qt5 installed only from packages, not from qt-project.org installer (only QtCreator I have installed from Qt Project site).
I hope this helps a bit. cezaryece
