As said above, you can't boot from a VM but. If you have a VM made with Fusion on a Mac you CAN run that VM on "bare metal" using one of VMware's enterprise versions. It is not quite the same as directly booting the VM but then there is no OS running under your VM either.
That is the best feature of VMware, Your VM made on a Mac can run under Linux or "whatever". The VM's are portable. I use this feature all the time. I keep a VM on an external disk and can run it at work on a high end Linux system using VM Workstation or at home using Fusion.