Comment 13 for bug 704231

This also prevents VirtualBox from using superkey in window mode. To use the super key in VirtualBox, the guest has to be in fullscreen. IMHO I think this is a bad idea. I use the superkey for the virtualized guest as often as I do for the host.

I don't know if this is because of Unity, but this behavior did appear in 11.04 with Unity.