Eric Slivka at Mac Rumors:

MacRumors has now been able to obtain one of these iPad 3 displays and examine it under a microscope in an effort to determine whether it is indeed an ultra-high resolution Retina display. Physically, the purported iPad 3 display is the same size as the current iPad 1 and iPad 2 display at 9.7″ in diagonal, and looks quite similar to the naked eye.