So it seems Oracle is doing pretty good after taking over VirutalBox. I was for the first time able to make a guest OS X machine from a retail DVD which runs on both a Linux and Windows host. The only modification was to the .vbox XML file as follows:
<ExtraData> <ExtraDataItem name=”GUI/LastCloseAction” value=”powerOff”/> <ExtraDataItem name=”GUI/LastGuestSizeHint” value=”1024,768″/> <ExtraDataItem name=”GUI/LastNormalWindowPosition” value=”119,101,1024,810″/> <ExtraDataItem name=”VBoxInternal2/SmcDeviceKey” value=”ourhardworkbythesewordsguardedpleasedontsteal(c)AppleComputerInc”/> </ExtraData>
The original guide I used can be found here.