I remember the rumor about a "black" version. Everything they showed today appealed to having a white iPhone. I want to see how it pops on a black model as well. Upgrading to iOS 7 is a no-brainer for me tho.
In the Airdrop feature portion of the Keynote, they actually used a black iPhone 5 in the presentation. It was only displayed for 15 seconds and quickly gone after that. I grabbed a screenshot if you want it, but you can always go back and watch it.
It's built-in to several navigations apps like Navigon, TomTom, etcetera.
When you drive somewhere in the evening, the app uses a darker color scheme, and usually there's night time sky graphics and stuff.
Also, in iOS 6, the top bar changes color based on the app that's currently running. Or maybe it's an API, I'm not a developer.