virtualbox.org

Is it possible to login as another user that didn't create the VM's and administer the VM's? Right now when the user logs in and opens up VirtualBox Manager Console the list is empty.

If you have access to the VM's folder (read-write), then you simple goto the Machine -> Add... menu and point it to your .vbox, or double-click the .vbox. Careful if the permissions get reset every time you right the file (it happens on the Mac).

This method will not work as the VM will look as if it is "Powered Off" (But in fact it is running under another user). I've tried this and get an error message when trying to start the vm: "Failed to open a session for the virtual machine TEST"

If you can think of a scenario that you could do that with a physical machine, you could most probably do it with a virtual machine (XServer over ssh, RDP). Think of your virtual machine as another computer in your network.