It may be worth mentioning that Siri is already pretty accessible through existing, widely available Bluetooth hands-free support. Both with my Nissan LEAF's stock system and my RAV4's Pioneer aftermarket system, I can reach over and hold down the home button on my iPhone to initiate voice interaction with Siri though the car's microphone and speakers (as opposed to the phone's). The a/v system mutes the current audio and Siri chirps and I can make vocal requests for info, send a message or whatever and the answers come back through the car speakers. That's just Bluetooth support. So it's reasonable to expect at least this level of "integration" with the Model S. Though of course how well that works in the presence of noise is largely dependent on your car's microphone and noise cancellation. The LEAF's works great...