Czech website superiphone.cz have obtained a screen they claim is from the iPhone 4/iPhone HD, and rather than just run some photos, they’ve done an analysis of it. Putting the part under a microscope, they’re saying it’s an IPS panel, with a pixel density of 960×640, some 4x the current model. That’s around 330 pixels per inch, the highest of any phone on the market, and the iPhone 3GS has around 160 ppi.
This is in line with the assumed specifications of the new device, and not surprising. You can be sure that content on a screen this high resolution will absolutely gorgeous!