It may not be "World Backup Day" by the letter of the law, but it might as well be in spirit. iOS 7 is due to drop tomorrow, and we at TUAW would gently like to remind you to perform a backup before the new firmware is released.
You'll want a clean, recent copy of all your files (especially all those levels you so laboriously earned and all your precious media like the pics of your pets and kids, not to mention those awesome barista swirls).
We recommend connecting your iPhone to a computer and using the manual "Back Up Now" option, so you can be sure that all your data and all your media is safely copied.
Happy upgrades everyone!