Confirmed. iPhone 4S is compatible with iPhone 4 card reader.October 14th, 2011 by Derek & Ryan
We’ve now had an opportunity to test the iPhone 4S with our iPhone 4 reader, and it’s good to go. If you’re upgrading your iPhone, you can find the iPhone 4 / iPhone 4S reader in our store.
And to celebrate, here’s a coupon for $20 off that reader (good through the weekend): IPHONE4S20