HMD (Head Mounted Displays) have been used in VBS for quite a long time ...

http://www.virtualsimulationsystems.com/www/index.php?option=com_content&view=article&id=52&Itemid=139

No doubt the Oculus is being looked at ;)

It actually makes you quite sick after only a short period of using it. :)

And on their website they say that you should never use it after drinking alcohol ... or you WILL vomit !

Support for it to be modded in would be rather difficult actually since it relies on a very specific rendering solution that requires you to grab the rendering info pre the projection matrix, and then render this to the two separate eye pieces (with calculated FOV and offsets based upon interpupilary distance and eye distance to the lens). It also requires a pixel shader to bend the image to counter act the barrel effect of the lenses.

Its definitely an engine job to get it working properly.

(I am working with one of the headsets at the moment on another project)