Now that I see it, I'm wondering why no one thought of this before.
A company called Rydeen is demonstrating a prototype car stereo that runs on the Andriod OS. But instead of being installed in the dash, it's intergarted into the rear-view mirror--a brilliant idea, especially when you consider how easy this would be to install and upgrade. Or steal, I supposed.
You can't buy one of these yet, but Rydeen hopes to have something on the market next year.
More on the unit can be found here.