Some non-Linux-dork posts are in the pipe, but today I had issues getting VirtualBox up and running on Gentoo. Here’s some proper install instructions to work around Bug 283617. I’ll get to fixing the ebuild later this weekend.
emerge virtualbox-bin chmod 4750 /opt/VirtualBox/VBoxNetAdpCtl chmod 4510 /opt/VirtualBox/VBoxSDL /opt/VirtualBox/VBoxHeadless /opt/VirtualBox/VirtualBox gpasswd -a youruser vboxusers
After a logout/login, VirtualBox should appear in your Applications menu, and can be run from the command line with VirtualBox.