I just got my hands on what is currently the highest resolution PenTile panel with pixels at 325 dpi. This resolution is very similar to the dpi in an iPhone 4. It is in a smartphone from a major brand supplier that is not Motorola.
As it turns out, this display is a PenTile RGBW LCD rather than a PenTile RGBG OLED. I measured the white luminance at about 400 nits.
Any guesses from the phone experts which phone this might be?