I learned this tip on Twitter the other day, I think from @marcoarment. I had never thought of encrypting my iPhone backup file, since any important data would already have been encrypted anyway. What he mentioned is that by encrypting your entire iOS backup, all your saved passwords will also be backed up. Without this option, they are left out of the backup file. Anyone who logs onto many wifi networks, web services, social networking apps, email accounts, etc will benefit from using this feature. It's located under your device's Summery tab within iTunes. The next time you upgrade your iPhone or iPad, or have to do a full restore, you won't be endlessly prompted to re-enter all of your passwords. Do your future-self a favor and check that box.