This is a brilliant idea from @chockenberry. Essentially, your iPhone would be able to know whether or not you are at home, and if you let it, adjust your settings accordingly. No more having to enter your passcode when nobody is going to steal your phone. No more leaving your phone set to loud, and having a silly ringtone embarrass you in work (this may or may not have happened to me...).
I remember my old Nokia phone had various settings, and you could switch between profiles really easily, but I only ever used three (loud, vibrate only, completely silent). This would be a midway point - a little more flexibility if you want it (especially with the passcode), but not over-complicated.