iPhone Insurance
Unfortunately, AT&T, which was the exclusive service provider for the iPhone does not offer insurance to cover it. On the website of AT&T, it states that the "iPhone is ineligible for the Wireless Phone Insurance program offered to AT&T customers. IPhone is covered by the Apple Warranty. If you have Wireless Phone Insurance from AT&T, it will be removed from your line of service."
Including it in your homeowner insurance policy would be one conceivable option.
However, here are two possible alternatives to insure your Apple iPhone.
First Option: Get an AppleCare Warranty when you buy the unit from Apple.

Second Option: Get a SquareTrade CarePlan.
SquareTrade has been in the market for 8 years now. The warranties they offer and provide are supported by an A-rated insurance firm. They are actually the principal provider of eBay's extended warranties. SquareTrade even has a management system online so that consumers can manage their warranties.
They do have a basic CarePlan planned out for the iPhone. The cost is 10% of the item's price, so it would be ranging from $49.99 to $59.99. This would depend on the kind of iPhone you bought from Apple. The insurance coverage would be the same as what you will get if you bought an AppleCare warranty. They have stated that if there is anything that happens to your iPhone, they can offer to fix it, or give you the full $499 to $599 value for replacement of the iPhone. They also guarantee that all repairs and replacements can be made within 5 days.
SquareTrade is also offering a superior CarePlan complete with an accidental damage coverage, which is not offered by the AppleCare warranty. Now this will be able to insure the phone in the event that you accidentally drop it. The accidental damage protection would cover any damage that results from crushing, cracking or dropping of the iPhone.
Keep in mind, though, that there are no insurance plans that will cover the phone in the event that you lose it, so make sure that you keep your eye on it always.