While updating my iPhone this morning, I noticed a line item that said the USB adapter on the Lightning camera connection kit will now work with the iPhone. I sold my old connection kit with my old iPad Mini, so I haven't been able to test it yet, but if it's true, this is great for photographers who enjoy a more mobile workflow.
Update: I finally had a chance to try it out, and can confirm it does work. I was able to quickly transfer RAW images from my EOS M to my iPhone 6s Plus. Sadly, Lightroom Mobile still doesn't support importing RAW images on the iPhone, though.