While this prototype that may or may not be a Treo 660 does not look significantly different than the Treo 600, take a closer look. The phone-first design is starting to come out even more. Not only does it look like a flattened Sony Eircsson T616, but the overall look and feel of the phone is about as trimmed down as a phone with a qwerty keypad can be.
It just screams “phone that also happens to be a PDA” so much more than the Treo 600 does.