Buyers of new iPhones (5c and 5s) will get iOS 7 pre-installed of course, but they likely will have to update to iOS 7.01 as soon as they are unwrapped. 9to5Mac and others sites are reporting there will be an update pushed through Apple servers on Friday, the day the new phones launch.
The update will reportedly fix a bug with the touch ID system and iTunes purchases. Apple has said the new fingerprint detection will work to make app store purchases.
It isn't known for sure if there is anything in the update for iPhone users who aren't using the newest iPhones. We'll find out Friday.