Today, Apple informed their iPhone developers that the corporation is now requiring them to submit screenshots of their applications at the Retina resolution (960 x 640 pixels) as means of forcing developers to move towards the more HD specifications that the Retina display offers users. Updates to current apps must also include these new enhanced Retina screenshots. So, if you’re a developer then it’s recommended that you optimize your app for the Retina display and update it as soon as possible. You’ll get better ratings and Apple will actually allow you to keep it in the store as well.
Required iPhone & iPod touch Screenshot Upgrade for Retina Display
When you create or update your apps in iTunes Connect, you must upload screenshots that are high-resolution. We require your screenshots as high-resolution images so that your app is optimized for the Retina display.
The requirements for high-resolution images are 960 x 640, 960 x 600, 640 x 960, or 640 x 920 pixels. Images must be at least 72 dpi, in the RGB color space, and the file must be .jpeg, .jpg, .tif, .tiff, or .png. You can update your screenshot files at any time in iTunes Connect.