We need a tough IPX7 rated polycarbonate with Gorilla glass overlaying the touchscreen and a wired power and audio ports. A case with a cradle perhaps like the Garmin Montana with the charging pins. I have the Rugged mount and I love how the pins allow easy docking and good weather resistance.
On the heat note, I'd be willing to bet an aluminum case conducts more heat to the phone then a plastic case. The glass needs to be UV resistant as well.