I know the Android app was available a few days ago. I just searched again on the iPhone app store and found the Tesla Model S App. You sign in with the same email and password as this website and it automatically links to your car. The menu includes Home, Controls, Charge, Climate, and Location across the bottom of the screen.
Home - shows current status, can sign in and out there.
Controls - vent roof, lock, unlock, honk horn, flash lights
Charge - switch from standard to max range, start and stop charging
Climate - shows current interior temp, turn climate on and off
Location - map view of the car location, direction to get to the car (goes to Maps app)
Thumbs up so far!