Apps on the iPhone can ship a ‘default.png’ in their bundle. When you start the app, it’ll first show this image, then load the rest of the app. The idea is, you can ship a picture of the start state of your app, and it’ll appear to have started very quickly. This is why some apps are unresponsive just after they start — they’re not actually started, you’re just looking at a picture. Other apps misuse this feature to display a splash screen. Urgh, splash screens.
Anyway, I digress. I have noticed that both the Contacts and Maps applications can change their default.png files.
Insam also reports that Maps will continue running in the background, until forced to quit from memory constraints. Another background-capable Apple app?