Reader BWJones, who is a retinal scientist, sends in this detailed analysis of the iPhone 4's "retinal display,"
which includes photomicrographs of the display pixels of earlier generations of iPhone as well as the iPad. Well worth a read. "... as you can see from these images of the displays I captured under a microscope, the pixels are not square. Rather they are rectangular, and while the short axis is 78 microns, the long axis on the iPhone 4 pixel is somewhere in the neighborhood of 102 microns. ... While [an earlier analysis by] Dr. Soneira was partially correct with respect to the retina, Apple's Retina Display adequately represents the resolution at which images fall upon our retina. ... [I] find Apple's claims stand up to what the human eye can perceive."