According to Raymond Soneira, president of DisplayMate Technologies, the resolution of the actual human retina is higher than claimed by Apple, working out to 477 pixels per inch at 12 inches (305 mm) from the eye.[5] Phil Plait of Bad Astronomy wrote a response saying that "if you have [better than 20/20] eyesight, then at one foot away the iPhone 4's pixels are resolved. The picture will look pixellated. If you have average eyesight [20/20 vision], the picture will look just fine," and concluded, "So in my opinion, what Jobs said was fine. Soneira, while technically correct, was being picky."[6] Retinal neuroscientist Bryan Jones, using a similar but more detailed analysis, came to a similar conclusion on his blog, stating "...Id find Apples claims stand up to what the human eye can perceive."[7]
http://en.wikipedia.org/wiki/Retina_Display