iOS 7 Lock screen Bug?
If you have different background images on your lock screen and home screen and have passcode lock off, you can make your home screen background image appear on the lock screen. Slide to unlock as usual, but just before the phone unlocks slide back. If done correctly, the background you have on your home screen will now be the background image on the lock screen until you completely unlock your phone.
This work on my iPhone 4s running iOS 7.0.2. It's kind of hard to explain, but try it out and see if you can do it. Maybe this is something that has been around for a while and everybody knows about it, but I got very surprised when I accidentally managed to do this.