The good news is, this trick isn't limited to your iPhone. You can change the language settings on nearly all of your gadgets: your Nintendo DS, your TV, and even your computer. When you're trying to learn (or re-learn) a language, every little bit helps.
I've heard that the way to learn a language quickly is to immerse yourself in it, and although you may not be able to move to the country of your choice, adjusting small things in your everyday life can help you learn and remember a language more efficiently. For example, did you know that PetSugar speaks Italian? Neither did I, until she told me she changed the default language on her iPhone to Italian. Sure, she's already familiar with the icons, but now she can start reading and recognizing the language every day.