One good accessory purchase for any iPhone buyer is AppleCare, but now Apple has upped the ante with a new product called AppleCare+ -- they'll now cover accidental damage to your iPhone.
AppleCare+ ($US99) must be purchased at the same time that you buy your new iPhone, and covers up to two incidents of damage due to handling errors. For each of those incidents, Apple will extract a $49 service fee, but that's a lot less expensive than purchasing a whole new iPhone.
AppleCare+ is available for purchase now, and shows a delivery date of October 14 -- the date that the first iPhone 4S devices will be available.