It has been brought into question as to whether Microsoft's Project Natal struggles to interpret the movements of people with dark skin.
The alarm was first raised when Bitmob first reported on former Newsweek writer N-Gai Croal having difficulties with Microsoft's controller-less motion-sensing camera.
Research has actually been performed on the difficulties that near-infra-red cameras (Project Natal features an infra-red camera) have with dark skin, with the following study finding that the technology does indeed have more difficulty with darker skin.
[UPDATE] - Microsoft has responded to these concerns in the following story:
Microsoft: Natal will work for all ethnicities at launch