I don't have an iPhone, but while it's sold as iPhone, It doesn't seem to use anything other than an earphone jack.
See this as a good way to talk to someone while using your phone to navigate. Perfect for boring conversations with in laws, colleagues, Kris Kringle present or when there is no other media device around to distract you when you're on a boring call!
Looks made for the 30pin connector, but doesn't necessarily need to be limited to this.
Shipping is currently $7.97 but will be free at 7pm on 17.11 with clickfrenzy sale.
Closer pic here: http://img1.dealsdirect.com.au/prod/EL738-BLACK/1z.jpg
Update: Only real negative that I see is the newer phone's earphone jack location is now at the bottom of the phone :(
Maybe some re engineering of the cradle could work!
Enjoy!
Can't see why not! Updated description & title :)