Installed an announced VirtualBox version 2.2.2 but could not run it (Fedora 10).
This is an updated post, please read on.
VirtualBox: supR3HardenedMainGetTrustedMain: dlopen("/usr/lib/virtualbox/VirtualBox.so",) failed: /usr/lib/virtualbox/VirtualBox.so: undefined symbol: _ZN11QTreeWidget17setSelectionModelEP19QItemSelectionModel
Googling does not offer any solution yet, lots of people reported same problem (the update seems to start to be available only 2 days before).
Downgraded to VirtualBox version 2.2.0 for now.
Version 2.2.4 is out, cleanly installs over 2.2.0 with:
sudo yum localinstall --nogpgcheck VirtualBox-2.2.4_47978_fedora9-1.x86_64.rpm
The above bug is gone. Seems to run smoothly for now but I am still keeping a stable 2.2.0 package.