Do you want your iPhone apps sharpened up for iPhone 4's Retina Display? iPhone 4 has a whopping 960x480 screen which is literally 4 times (twice vertical, twice horizontal) the pixel size, but the same physical size, as previous generation iPhone 2G, iPhone 3G, and iPhone 3GS. That's a density of over 300dpi -- print magazine quality. Existing apps will just seamlessly use 4 pixels on the iPhone 4 compared to 1 pixel on previous gen iPhones, so they'll look identical.