V Australia (a new Australia-USA airline) planes have this feature. The lighting inside the plane varies depending on the time of 'day' they want you to think it is. They often ask to have the window shades closed to enhance the effect. The colours aren't completely natural - they range from a deep blue (daylight) to an orange (sunset/sunrise) to a purple-blue (nightime). It's all done gradually and very subtle.

Subjectively it helped me to adjust to the different timezone during the flight, but it might have just been the 'hey, neato' factor as well.