It looks like Occulus Rift has just hired a VR expert to help get rid of motion sickness in their vr kit: Here is a link to the article

For those new to VR and wonder about why the motion sickness happens, here is an explanation from sciencedaily.com:

“Years ago research showed that the brain can re-set an upside-down view of world to be right side up. Constantly changing images pose a bigger challenge for the brain, which has to deal with ‘lag’: the time it takes the computer system to update and display changing visual images corresponding to the users head movements. This may be a variable linked to motion sickness and other symptoms related to helmet-mounted devices.”