From Apple’s product page:
CarPlay takes the things you want to do with your iPhone while driving and puts them right in your car’s built-in display. You can get directions, make calls, send and receive messages, and listen to music, all in a way that allows you to stay focused on the road.
Select cars from Ferrari, Honda, Hyundai, Jaguar, Mercedes-Benz, and Volvo that support CarPlay will be shipping this year with models from other car manufacturers coming later in the future.
I would love for there to be third-party head units that support CarPlay in the future. I purchased my Toyota Camry a few years ago and plan on keeping it for another decade or more. And, that’s a long time to wait for device integration that’s better than my current audio cable and auxiliary-in jack setup that I’m using now.