Neil Hughes:

Apple has explored building displays with dynamic backlight adaptation for better picture quality, particularly when watching letterboxed widescreen movies on a high-definition screen.

This is based on an Apple patent that depicts what could be a television screen that would use dynamic backlighting to keep darker areas of the screen (or black bars in letterboxed movies) darker by dimming the backlighting in those areas.

But Apple patents everything they think of, so this in no way confirms that Apple will use this technology in their television.