Apple has released another commercial in the "If you don't have an iPhone" series of ads. This commercial, titled "Retina," shows off the Retina Display on the iPhone 4. The ad cycles through the Photos, iPod (movies), Maps, and Mail apps. The latest ad comes just one day afterApple released an iPhone 4 ad showcasing Game Center. Apple seems to release iPhone ads in groups of twos or threes, so it's likely that another one may hit the airwaves soon.