I have a rider with State Farm. Only cost about $30-35/year. All State Farm wants is if the handset cost $300 or more (if my memory serves). I just remember there was a cost factor involved. I use it to cover all the family's cell phones and my laptop.
You better check to be sure that policy is still in place. They cancelled my policy on my Treo 650, and when I recently updated my insurance on my MacBook Pro I asked about the iPhone and was told they will not cover any smartphone, PDA, etc. on a personal property rider.
I just paid my premium again for the year. It is still in place. As I said earlier, a lot had to do with the cost of the device, as they had recently put a requirement that the item have a certain initial value. I hope that helps you.
I have a 1st Generation iPhone, and actually called my State Farm agent the other day. They told me that they'd insure my iPhone and laptop both for 30 bucks a year. All I have to do is get my receits out and take them to StatecFarm, which Im planning on doing tomorrow.