Google Earth for iOS, which was already one of the biggest "wow" apps on the iPhone (It's the Earth in your pants!), has received a huge update that adds support for the iPhone 4's gorgeous retina display, as well as new ocean topographies that will allow users to explore the underwater depths.
You can see from the screenshot above that this adds an insane amount of detail to the textures and drawing space. Even this comically oversized screen grab can't convey how good this looks on a real iPhone 4, though. I highly suggest that you check it out for yourself.
Google Earth is a universal application for iPhone, iPad and iPod touch; it is available in the App Store as a free download.