A developer has broken his NDA with Apple to show the world a dynamic iOS 7 Clock icon which displays the real time. You can have two clocks on iOS 7’s Home screen.
This developer told TUAW that the iOS 7 Clock app icon shows the current time, complete with moving second hand, so you can see the clock ticking by the second.
Apple could make other iOS 7 icons just as dynamic, including Weather (to show the current temperature, or whatever the user sets it to display in-icon), Maps (to show a preview of a certain route), and even the Videos app icon (to show a preview of the current-playing video).
In fact, according to a bunch of leaked icons on Apple.com, the company once considered making the Weather app dynamic to show the current temperature without having to actually launch the app.