Today seems like a customization day, and bodysoulspirit makes a iOS7 screensaver, however the installer is only for ML/Mavericks. With some tweaking with help from jrsx, I was able to compile a pack so you can do this too! This is for Leopard only, Tiger has some issues.
Download the pack here, and put “iOS7 lockscreen by bodysoulspirit.qtz” in /System/Library/Screen Savers. Now go change your screensaver and it’s there! You can customize it to your liking.
Updated 1/2/2017: The old download link was hosted on a file server that no longer exists, however the screensaver is saved in Google Drive so we will always have it 🙂