Fedora12
Use the original rpm-s from http://www.virtualbox.org/wiki/Linux_Downloads.
sudo rpm --import oracle_vbox.asc wget -q "http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc" -O- | rpm --import - rpm --checksig PACKAGE_NAME
Repo is available: http://download.virtualbox.org/virtualbox/rpm/fedora/virtualbox.repo