Everyone knows that "Retina Display" is a fake thing, right? Its just a marketing slogan that Apple uses to describe the fact that the screen has somewhat higher pixel density than their competitors, currently, and bound to change in the near future. I always detect some confusion about this form posters on this forum.
Higher pixel density is great, but "Retina Display" is not a technology. It is a marketing slogan.
Have you ever looked at the display on the iPhone 4? If not, then go spend some time with one and you'll understand where they're coming from with the term.
The pixels are so dense, that most human eyes lose the ability to discern the individual pixels when viewed at a normal viewing distance. Hence it's a display that matches the retina's resolution - as far as our eyes are concerned, it's a smooth picture with no gaps at all.
Retina display is a marketing term, but it happens to be one that describes the product pretty nicely, especially for those lay peole who don't understand the advantages of high pixel density (which is a lot of people - just look at how many people would buy a bigger PC monitor even if the resolution is the same or lower than another display that's 2" smaller)