Using OnStar’s Voice-Activated Hands-Free Calling system, and having your voice converted into text, you can provide updates which would appear in the “What are you doing?” section of your Twitter homepage. It is also possible to listen to a tweet that was sent to you by someone else after it has been converted into voice. You can send and receive tweets without having to type or read anything.”
This is fascinating. We've talked about Twitter morphing into a DA-like, social directory service where you ask your "followers" for recommendations and receive them in near real time. This potential in-car integration would further that use case for sure.
And just because it's so good, here's the Twitter send-up from Current TV: "We've wasted our lives."