Well you require a really powerful machine to get a good Virtual Reality experience. Good graphics, with good framerate.
While powerful consumer machines get smaller and require less power, I do not see that a powerful enough machine to drive an immersive Virtual Reality world will come in a portable form, short of a laptop in a backpack. No pocket sized VR simulator yet.
For demonstration of what you can run on your phone today, you can look at quake or arena, rendered steroscopically and with head tracking. But for me this is a novelty. especially after trying the awesome experience that is http://vrmods.wordpress.com/