virtualbox.org

I saw a few threads concerning converting an existing installation into a VM, but that's not quite what I'm looking for. I'm wondering if it's possible to use your dual boot partition as a virtual machine AND as a seperate OS concurrently. In other words, being able to choose if you want to boot the secondary OS, or run it in a VM, and be able to go back and forth as needed. I did see that VMWare Workstation has this functionality, here is some documentation related to the subject http://www.vmware.com/support/ws45/doc/ ... ot_ws.html
Just wondering if VirtualBox has an equivalent?